Fair Value Disclosures [Abstract] Summary of Assets and Liabilities Measured at Fair Value Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Reconciliation of the Beginning and Ending Balances of Assets and Liabilities Measured at Fair Value Using Significant Unobservable, or Level 3, Inputs Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table Text Block] Acquisitions, Disposals and Discontinued Operations [Abstract] Acquisitions, Disposals and Discontinued Operations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] SFR BeLux [Member] SFR BeLux [Member] SFR BeLux [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Telenet [Member] Telenet [Member] Telenet [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Consideration transferred Business Combination, Consideration Transferred Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Schedule of Fair Values of Derivative Instrument Assets and Liabilities Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Realized and Unrealized Losses on Derivative Instruments Schedule Of Realized And Unrealized Gains Losses On Derivative Instruments Text Block Schedule Of Realized And Unrealized Gains Losses On Derivative Instruments. Schedule of Cash Received (Paid) Related to Derivative Instruments Statement of Cash Flows Location Schedule Of Cash Received Paid Related To Derivative Instruments Statement Of Cash Flows Location Text Block Schedule Of Cash Received Paid Related To Derivative Instruments Statement Of Cash Flows Location. Schedule of Derivative Instruments Schedule of Derivative Instruments [Table Text Block] Accounting Changes and Error Corrections [Abstract] Schedule of New Accounting Pronouncements and Changes in Accounting Principles Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Long-lived Assets [Abstract] Long lived Assets [Abstract] Long-lived Assets Long Lived Assets Disclosure [Text Block] The entire disclosure for long-lived assets. Operating activities Payments for (Proceeds from) Derivative Instrument, Operating Activities Payments for (Proceeds from) Derivative Instrument, Operating Activities Financing activities Payments for (Proceeds from) Derivative Instrument, Financing Activities Total Payments For Proceeds From Derivatives Continuing Operations Payments For Proceeds From Derivatives Continuing Operations Statement of Comprehensive Income [Abstract] Statement [Table] Statement [Table] Operating Activities [Axis] Operating Activities [Axis] Operating Activities [Domain] Operating Activities [Domain] Continuing Operations [Member] Continuing Operations [Member] Discontinued Operations [Member] Discontinued Operations [Member] Statement [Line Items] Statement [Line Items] Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive earnings, net of taxes: Other Comprehensive Income (Loss), Net of Tax [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Pension-related adjustments and other Other Comprehensive Income Defined Benefit Plans Adjustment And Derivatives Qualifying As Hedges Net Of Tax Period Increase Decrease Other Comprehensive Income Defined Benefit Plans Adjustment And Derivatives Qualifying As Hedges Net Of Tax Period Increase Decrease Other comprehensive earnings from continuing operations Other Comprehensive Income (Loss), Net of Tax Comprehensive loss Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive earnings attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive loss attributable to Liberty Global shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Debt and Capital Lease Obligations [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] VM Notes [Member] VM Notes [Member] VM Notes [Member] VM Credit Facilities [Member] VM Credit Facility [Member] VM Credit Facility [Member] Unitymedia Notes [Member] Unitymedia Notes [Member] Unitymedia Notes [Member] Unitymedia Credit Facilities [Member] Unitymedia Credit Facilities [Member] Unitymedia Credit Facilities [Member] UPCB SPE Notes [Member] UPCB SPE Notes Debt [Member] UPCB SPE Notes Debt [Member] UPC Holding Bank Facility [Member] UPC Holding Bank Facility Debt [Member] UPC Holding Bank Facility Debt [Member] UPC Holding Senior Notes [Member] UPC Holding Senior Notes Debt [Member] UPC Holding Senior Notes Debt [Member] Telenet Credit Facility [Member] Telenet Credit Facility [Member] Telenet Credit Facility [Member] Telenet Senior Secured Notes [Member] Telenet Senior Secured Notes [Member] Telenet Senior Secured Notes [Member] Telenet SPE Notes [Member] Telenet SPE Notes [Member] Telenet SPE Notes [Member] Vendor Financing [Member] Vendor Financing [Member] Vendor Financing [Member] ITV Collar Loan [Member] ITV Collar Loan [Member] ITV Collar Loan [Member] Sumitomo Share Loan [Member] Sumitomo Share Loan [Member] Sumitomo Share Loan [Member] Derivative-related debt instruments [Member] Derivative Related Debt Instruments [Member] Derivative Related Debt Instruments [Member] Sumitomo Collar Loan [Member] Sumitomo Collar Loan Debt [Member] Sumitomo Collar Loan Debt [Member] Other [Member] Other Debt [Member] Other Debt [Member] Aggregate Variable and Fixed Rate Indebtedness [Member] Aggregate Variable and Fixed Rate Indebtedness [Member] Aggregate Variable And Fixed Rate Indebtedness [Member] VM Revolving Credit Facility [Member] VM Revolving Credit Facility [Member] VM Revolving Credit Facility [Member] VM Revolving Facility A [Member] VM Revolving Facility A [Member] VM Revolving Facility A [Member] VM Revolving Facility B [Member] VM Revolving Facility B [Member] VM Revolving Facility B [Member] Telenet Facility AG [Member] Telenet Facility AG [Member] Telenet Facility AG [Member] Telenet Facility AL Add-on [Member] Telenet Facility AL Add-on [Member] Telenet Facility AL Add-on [Member] Telenet Overdraft Facility [Member] Telenet Overdraft Facility [Member] Telenet Overdraft Facility [Member] Telenet Revolving Facility [Member] Telenet Revolving Facility [Member] Telenet Revolving Facility [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Significant other observable inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Virgin Media [Member] Virgin Media [Member] Virgin Media [Member] Unitymedia [Member] Unitymedia [Member] Unitymedia [Member] UPC Holding [Member] UPC Holding [Member] UPC Holding [Member] Other [Member] Other Subsidiaries [Member] Relating to Other Subsidiaries not otherwise identified. 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of Vendor Financing Arrangements for Amounts Due General Term of Vendor Financing Arrangements for Amounts Due Debt Long-term Debt, Fair Value Number of borrowing groups Number of Borrowing Groups Number of Borrowing Groups Equity [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Class A and Common Class C [Member] Common Class A and Common Class C [Member] Common Class A and Common Class C [Member] Common Class A [Member] Common Class A [Member] Common Class C [Member] Common Class C [Member] Class of Stock [Line Items] Class of Stock [Line Items] Shares repurchased (in shares) Stock Repurchased and Retired During Period, Shares Average price paid per share (in dollars per share) Treasury Stock Acquired, Average Cost Per Share Total cost Payments for Repurchase of Common Stock Remaining authorized repurchase amount Stock Repurchase Program, Remaining 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Swaption 2 [Member] Interest Rate Swaption 2 [Member] Interest Rate Swaption 2 [Member] Interest Rate Swaption [Member] Interest Rate Swaption [Member] Derivative [Line Items] Derivative [Line Items] Notional amount of derivative Derivative, Notional Amount Weighted average remaining life Derivative, Average Remaining Maturity Weighted average strike rate Derivative, Average Swaption Interest Rate Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Network and Connectivity Commitments [Member] Network and Connectivity Commitments [Member] Network and Connectivity Commitments [Member] Programming Commitments [Member] Programming Commitments [Member] Programming Commitments [Member] Purchase Commitments [Member] Purchase Commitments [Member] Purchase Commitments [Member] Operating Leases [Member] Operating Leases [Member] Operating Leases [Member] Other Commitments [Member] Other Commitments [Member] Other Commitments [Member] Unrecorded Unconditional Purchase Obligation [Line Items] Unrecorded Unconditional Purchase Obligation [Line Items] Remainder of 2018 Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year 2019 Unrecorded Unconditional Purchase Obligation, Due within Two Years 2020 Unrecorded Unconditional Purchase Obligation, Due within Three Years 2021 Unrecorded Unconditional Purchase Obligation, Due within Four Years 2022 Unrecorded Unconditional Purchase Obligation, Due within Five Years 2023 Unrecorded Unconditional Purchase Obligation Balance On Sixth Anniversary Unrecorded Unconditional Purchase Obligation Balance On Sixth Anniversary Thereafter Unrecorded Unconditional Purchase Obligation Balance On Sixth Anniversary And Thereafter Unrecorded unconditional purchase obligation balance on sixth anniversary and thereafter. Total Unrecorded Unconditional Purchase Obligation Schedule of Goodwill [Table] Schedule of Goodwill [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments [Member] Operating Segments [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] U.K./Ireland [Member] U.K. / Ireland [Member] U.K. / Ireland [Member] Belgium [Member] BELGIUM Germany [Member] GERMANY Switzerland/Austria [Member] Switzerland / Austria [Member] Switzerland / Austria [Member] Central and Eastern Europe [Member] Central and Eastern Europe [Member] Central and Eastern Europe [Member] Central and Corporate [Member] Central and Corporate [Member] Central and Corporate [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] January 1, 2018 Goodwill Acquisitions and related adjustments Goodwill, Purchase Accounting Adjustments Foreign currency translation adjustments Goodwill, Foreign Currency Translation Gain (Loss) March 31, 2018 Statement of Cash Flows [Abstract] Reconciliation of end of period cash and cash equivalents and restricted cash — continuing operations: Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash included in other current assets Restricted Cash, Current Restricted cash included in other assets, net Restricted Cash, Noncurrent Total cash and cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Accrued Income Taxes [Abstract] Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Domestic Tax Authority [Member] Domestic Tax Authority [Member] Income Taxes [Line Items] Income Taxes [Line Items] [Line Items] for Income Taxes [Table] Income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 2017 U.S. Tax Cuts and Jobs Act, provisional liability recorded Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Liability Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Liability Unrecognized tax benefits Unrecognized Tax Benefits Unrecognized tax benefits that would have a favorable impact Unrecognized Tax Benefits that Would Impact Effective Tax Rate Decrease in unrecognized tax benefits reasonable possible amount Decrease in Unrecognized Tax Benefits is Reasonably Possible Income Taxes Income Tax Disclosure [Text Block] Restructuring and Related Activities [Abstract] Restructuring Liability Restructuring and Related Activities Disclosure [Text Block] Investments [Abstract] Schedule of Investments by Accounting Method Schedule of Investments by Accounting Method [Table Text Block] Schedule of Investments by Accounting Method [Table Text Block] Equity Method Investments Equity Method Investments [Table Text Block] Fair Value, Assets and Liabilities (Net) Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Investments [Member] Investments [Member] Cross-Currency and Interest Rate Derivative Contracts [Member] Cross-Currency and Interest Rate Derivative Contracts [Member] Cross-Currency and Interest Rate Derivative Contracts [Member] Equity-Related Derivative Instruments [Member] Equity-Related Derivative Instruments [Member] Equity-Related Derivative Instruments [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Balance of net assets at January 1, 2018 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Gains included in net earnings (loss) Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings [Abstract] Realized and unrealized (gains) losses, net Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Additions Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Impact of ASU 2016-01 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Impact of ASU Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Impact of ASU Foreign currency translation adjustments and other, net Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Balance of net assets at March 31, 2018 2018 (remainder of year) Capital Leases, Future Minimum Payments, Remainder of Fiscal Year 2019 Capital Leases, Future Minimum Payments Due in Two Years 2020 Capital Leases, Future Minimum Payments Due in Three Years 2021 Capital Leases, Future Minimum Payments Due in Four Years 2022 Capital Leases, Future Minimum Payments Due in Five Years 2023 Capital Leases, Future Minimum Payments Due in Six Years Contractually required rental payments on leases meeting the criteria for capitalization, due within the fifth year from the balance sheet date. Thereafter Capital Lease Future Minimum Payments Due After Year Six Contractually required rental payments on leases meeting the criteria for capitalization, due after the sixth year from the balance sheet date. Total principal and interest payments Capital Leases, Future Minimum Payments Due Amounts representing interest Capital Leases, Future Minimum Payments, Interest Included in Payments Present value of net minimum lease payments Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments Current portion Capital Lease Obligations, Current Noncurrent portion Capital Lease Obligations, Noncurrent Revenue from Contract with Customer [Abstract] Trade receivables, allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Contract assets Contract with Customer, Asset, Net Deferred revenue Deferred Revenue Revenue recognized Contract with Customer, Liability, Revenue Recognized Aggregate assets associated with incremental costs to obtain a contract and contract fulfillment costs Capitalized Contract Cost, Net Amortization related to contract costs Capitalized Contract Cost, Amortization Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Residential Service and Mobile [Member] Residential Service and Mobile [Member] Residential Service and Mobile [Member] Business to Business [Member] Business to Business [Member] Business to Business [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Unsatisfied performance obligations term Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Distribution Systems [Member] Distribution Systems [Member] Distribution Systems [Member] Customer Premises Equipment [Member] Customer Premises Equipment [Member] Customer Premises Equipment [Member] Support Equipment, Buildings and Land [Member] Support Equipment, Buildings and Land [Member] Support Equipment, Buildings and Land [Member] Property and equipment, gross Property, Plant and Equipment, Gross Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total property and equipment, net Property, Plant and Equipment, Net Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Employees [Member] Employees [Member] Employees [Member] Former Employees [Member] Former Employees [Member] Former Employees [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Options and SARs [Member] Options and Share Appreciation Rights (SARs) [Member] Options and Share Appreciation Rights (SARs) [Member] RSUs [Member] Restricted Stock Units (RSUs) [Member] PSUs [Member] Performance Shares [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Options outstanding (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options outstanding, weighted average exercise or base price (in dollars per shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options exercisable, weighted average exercise price or base price (in dollars per shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Other than options outstanding (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Foreign Currency Forwards and Option Contracts [Member] Foreign Exchange Forward [Member] Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] VodafoneZiggo JV [Member] VodafoneZiggo JV [Member] VodafoneZiggo JV [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Total consolidated property and equipment additions Property, Plant and Equipment, Additions Assets acquired under capital-related vendor financing arrangements Assets Acquired Under Capital-Related Vendor Financing Arrangements Assets Acquired Under Capital-Related Vendor Financing Arrangements Assets acquired under capital leases Capital Lease Obligations Incurred Changes in current liabilities related to capital expenditures Increase Decrease in Current Liabilities Related to Capital Expenditures Increase Decrease in Current Liabilities Related to Capital Expenditures Total consolidated capital expenditures Payments for Capital Improvements Property and equipment additions - VodafoneZiggo JV Equity Method Investment, Summarized Financial Information, Payment to Acquire Property, Plant and Equipment Equity Method Investment, Summarized Financial Information, Payment to Acquire Property, Plant and Equipment Basis Swap [Member] Basis Swap [Member] Interest Rate Cap [Member] Interest Rate Cap [Member] Interest Rate Collar [Member] Interest Rate Collar [Member] Interest Rate Collar Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Parent Company [Member] Parent Company [Member] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Performance-Based Incentive Awards [Member] Performance-Based Incentive Awards [Member] Performance-Based Incentive Awards [Member] Non-Performance Based Share-Based Awards [Member] Non-Performance Based Share-Based Awards [Member] Non-Performance Based Share-Based Awards [Member] Other Share-Based Incentive Awards [Member] Other Share-Based Incentive Awards [Member] Other Share-Based Incentive Awards [Member] Telenet Share-Based Incentive Awards [Member] Telenet Share-Based Incentive Awards [Member] Telenet Share-Based Incentive Awards [Member] Other Stock Plan [Member] Other Stock Plan [Member] Other Stock Plan [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Operating Income (Expense) [Member] Other Operating Income (Expense) [Member] Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Stock-based compensation expense Allocated Share-based Compensation Expense Cross-currency and interest rate derivative contracts [Member] Cross Currency Interest Rate Contract [Member] Equity-related derivative instruments [Member] Equity Contract [Member] ITV Collar [Member] ITV Collar [Member] ITV Collar [Member] Sumitomo Collar [Member] Sumitomo Collar [Member] Relating to the Sumitomo Collar Lionsgate Forward [Member] Lionsgate Forward [Member] Lionsgate Forward [Member] Other [Member] Other Equity Related Derivative Instrument [Member] Other Equity Related Derivative Instrument [Member] Other [Member] Other Contract [Member] Gain (loss) on derivative instruments, net Derivative, Gain (Loss) on Derivative, Net Liberty Puerto Rico [Member] Liberty Puerto Rico [Member] Liberty Puerto Rico [Member] Impact of derivative instruments on borrowing costs Impact of Derivative Instruments on Borrowing Costs, Percent Increase (Decrease) Impact of Derivative Instruments on Borrowing Costs, Percent Increase (Decrease) Segment Reporting, Measurement Disclosures [Abstract] Segment Reporting Segment Reporting Disclosure [Text Block] Investment [Table] Investment [Table] Other [Member] Other Unnamed Investment [Member] Other Unnamed Investment [Member] ITV — subject to re-use rights [Member] ITV - Subject to Re-Use Rights [Member] ITV - Subject to Re-Use Rights [Member] Sumitomo [Member] Sumitomo [Member] Sumitomo [Member] ITI Neovision [Member] ITI Neovision [Member] ITI Neovision [Member] Lionsgate [Member] Lionsgate [Member] Lionsgate [Member] Casa Systems, Inc. (Casa) [Member] Casa Systems, Inc. (Casa) [Member] Casa Systems, Inc. (Casa) [Member] Investment [Line Items] Investment [Line Items] Equity Equity Method Investments Fair value Investments, Fair Value Disclosure Cost Cost Method Investments Total Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Share of losses of affiliates, net Income (Loss) from Equity Method Investments Summarized results of operations of the VodafoneZiggo JV Equity Method Investment, Summarized Financial Information [Abstract] Revenue Equity Method Investment, Summarized Financial Information, Revenue Loss before income taxes Equity Method Investment, Summarized Financial Information, Income (Loss) from Continuing Operations Net loss Equity Method Investment, Summarized Financial Information, Net Income (Loss) Noncash vendor financing arrangement, cash increase, excluding value added tax Property Plant And Equipment, Additions, Vendor Financing Arrangement Property Plant And Equipment, Additions, Vendor Financing Arrangement Value added tax, vendor financing arrangement Value Added Tax, Vendor Financing Arrangement Value Added Tax, Vendor Financing Arrangement Capital leases 2018 PSUs [Member] 2018 PSUs [Member] 2018 PSUs [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] April 1, 2020 [Member] April 1, 2020 [Member] April 1, 2020 [Member] October 1, 2020 [Member] October 1, 2020 [Member] October 1, 2020 [Member] Percent of annual incentive compensation receivable in shares Shareholder Inventive Program, Percent of Annual Incentive Compensation Shareholder Inventive Program, Percent of Annual Incentive Compensation Award grant (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Award performance period Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Period Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Period Award performance range Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Range Share-based Compensation Arrangement by Share-based Payment Award, Award Performance Range Award expected performance Share-based Compensation Arrangement by Share-based Payment Award, Award Expected Performance Share-based Compensation Arrangement by Share-based Payment Award, Award Expected Performance Award vesting rights Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Debt Disclosure [Abstract] Extinguishment of Debt [Axis] Extinguishment of Debt [Axis] Extinguishment of Debt, Type [Domain] Extinguishment of Debt, Type [Domain] Medium-term Notes [Member] Medium-term Notes [Member] Line of Credit [Member] Line of Credit [Member] Telenet Credit Facility AB [Member] Telenet Credit Facility AB [Member] Telenet Credit Facility AB [Member] Telenet Finance VI Notes [Member] Telenet Finance VI Notes [Member] Telenet Finance VI Notes [Member] Telenet Credit Facility V [Member] Telenet Credit Facility V [Member] Telenet Credit Facility V [Member] Telenet Finance V Notes [Member] Telenet Finance V Notes [Member] Telenet Finance V Notes [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Percentage of principal amount redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Extinguishment of debt Extinguishment of Debt, Amount Loss on debt modification and extinguishment Gain (Loss) on Extinguishment of Debt Payments for debt redemption premium Payments For Debt Redemption Premium Payments For Debt Redemption Premium Write-off of unamortized discounts and deferred financing costs Write-off of Unamortized Debt Discount and Deferred Financing Cost Write-off of Unamortized Debt Discount and Deferred Financing Cost Principal amount of debt Debt Instrument, Face Amount Schedule of Investments [Table] Schedule of Investments [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Equity Method Investee [Member] Equity Method Investee [Member] Vodafone [Member] Vodafone [Member] Vodafone [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] VodafoneZiggo JV Loan [Member] VodafoneZiggo JV Loan [Member] VodafoneZiggo JV Loan [Member] JV Services [Member] JV Services [Member] JV Services [Member] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Due from related party Receivable with Imputed Interest, Face Amount Receivable interest rate Receivable with Imputed Interest, Effective Yield (Interest Rate) Receivable in year one Receivable with Imputed Interest, Net Amount, Receivable in Year One Receivable with Imputed Interest, Net Amount, Receivable in Year One Receivable in year two Receivable with Imputed Interest, Net Amount, Receivable in Year Two Receivable with Imputed Interest, Net Amount, Receivable in Year Two Receivable in year three Receivable with Imputed Interest, Net Amount, Receivable in Year Three Receivable with Imputed Interest, Net Amount, Receivable in Year Three Accrued interests settled in cash Increase (Decrease) in Accrued Interest Receivable, Net Percent of interest income earned on loan included in investment Percent of Interest Income Earned on Loan Included in Income (Loss) from Equity Method Investments Percent of Interest Income Earned on Loan Included in Income (Loss) from Equity Method Investments Percent of share-based compensation included in investment Percent of Share-based Compensation Included in Income (Loss) from Equity Method Investments Percent of Share-based Compensation Included in Income (Loss) from Equity Method Investments Percent of remaining results of operations included in investment Percent of Remaining Results of Operations Included in Income (Loss) from Equity Method Investments Percent of Remaining Results of Operations Included in Income (Loss) from Equity Method Investments Ownership percentage Equity Method Investment, Ownership Percentage Co-venturer ownership percentage Equity Method Investment, Co-Venturer Ownership Percentage Equity Method Investment, Co-Venturer Ownership Percentage Dividends from affiliates and others Proceeds from Equity Method Investment, Distribution Proceeds from financing arrangements Proceeds from Joint Venture Debt Financing Arrangements Proceeds from Joint Venture Debt Financing Arrangements Proceeds from equalization payment from affiliate Proceeds from Equalization Payment from Affiliate Proceeds from Equalization Payment from Affiliate Value-added taxes (VAT) paid on behalf of the VodafoneZiggo JV Payments of Value-Added Taxes, Joint Venture Payments of Value-Added Taxes, Joint Venture Revenue Revenues Due from related party Due from Related Parties Schedule of PP&E Property, Plant and Equipment [Table Text Block] Schedule of Changes in Carrying Amount of Goodwill Schedule of Goodwill [Table Text Block] Schedule of Intangible Assets Subject to Amortization, Net Schedule of Finite-Lived Intangible Assets [Table Text Block] Investments Investment Holdings [Text Block] Schedule of debt Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Maturities of Debt Schedule of Maturities of Long-term Debt [Table Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Foreign currency forward and option contracts [Member] Foreign Exchange Contract [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Assets: Derivative Asset [Abstract] Current Derivative Asset, Current Long-term Derivative Asset, Noncurrent Total Derivative Asset Liabilities: Derivative Liability [Abstract] Current Derivative Liability, Current Long-term Derivative Liability, Noncurrent Total Derivative Liability Income Statement [Abstract] Revenue (notes 3, 5 and 16) Operating costs and expenses (exclusive of depreciation and amortization, shown separately below): Costs and Expenses [Abstract] Programming and other direct costs of services Cost of Services Other operating (note 12) Other Cost and Expense, Operating Selling, general and administrative (SG&A) (note 12) Selling, General and Administrative Expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Impairment, restructuring and other operating items, net (note 13) Restructuring, Settlement and Impairment Provisions Operating costs and expenses, Total Costs and Expenses Operating income Operating Income (Loss) Non-operating income (expense): Nonoperating Income (Expense) [Abstract] Interest expense Interest Expense Realized and unrealized losses on derivative instruments, net (note 6) Gain (Loss) on Derivative Instruments, Net, Pretax Foreign currency transaction gains (losses), net Foreign Currency Transaction Gain (Loss), before Tax Realized and unrealized gains (losses) due to changes in fair values of certain investments and debt, net (notes 5, 7 and 9) Realized And Unrealized Gains (Losses) Due To Changes In Fair Values of Certain Investments and Debt, Net Realized And Unrealized Gains (Losses) Due To Changes In Fair Values of Certain Investments and Debt, Net Losses on debt modification and extinguishment, net (note 9) Gains (Losses) on Restructuring of Debt Share of losses of affiliates, net (note 5) Other income, net Other Nonoperating Income (Expense) Non-operating income (expense), Total Nonoperating Income (Expense) Loss from continuing operations before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax expense (note 10) Income Tax Expense (Benefit) Loss from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Loss from discontinued operations, net of taxes (note 4) Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Loss from continuing operations Net earnings attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net loss attributable to Liberty Global shareholders Net Income (Loss) Attributable to Parent Basic and diluted loss from continuing operations attributable to Liberty Global shareholders per share (notes 1 and 13) (in dollars per share) Income (Loss) from Continuing Operations, Per Basic and Diluted Share Weighted average ordinary shares outstanding - basic and diluted (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted 2018 (remainder of year) Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year 2019 Long-term Debt, Maturities, Repayments of Principal in Year Two 2020 Long-term Debt, Maturities, Repayments of Principal in Year Three 2021 Long-term Debt, Maturities, Repayments of Principal in Year Four 2022 Long-term Debt, Maturities, Repayments of Principal in Year Five 2023 Long Term Debt Maturities Repayments of Principal in Year Six Amount of long-term debt maturing in year six following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed of determinable prices and dates. Thereafter Long Term Debt Maturities Repayments of Principal after Year Six Amount of long-term debt maturities after year six following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed of determinable prices and dates. Total debt maturities Long-term Debt, Gross Contractual Maturities Long-term Debt, Gross Contractual Maturities Deferred financing costs, discounts and premiums, net Total debt Long-term Debt Contractual Maturities Long-term Debt Contractual Maturities Current portion Long-term Debt, Current Maturities Noncurrent portion Long-term Debt, Excluding Current Maturities Common stock [Member] Common Stock [Member] Nonvoting Common Stock Nonvoting Common Stock [Member] Lionsgate Loan [Member] Lionsgate Loan [Member] Lionsgate Loan [Member] Counterparty Credit Risk [Member] Counterparty Credit Risk [Member] Counterparty Credit Risk [Member] Gain (loss) in changes in the credit risk valuation adjustments associated with our cross-currency and interest rate derivative contracts Gain Loss On Credit Risk Derivatives Net Recognized In Earnings Gain Loss On Credit Risk Derivatives Net Recognized In Earnings Number of common stock shares owned (in shares) Investment Owned, Balance, Shares Derivative assets Accounting Changes and Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Revenue Recognition and Related Costs Revenue Recognition, Policy [Policy Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities Excluded from Computation of Earnings Per Share, by Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Stock Options, SARs and RSUs [Member] Stock Options, SARs and RSUs [Member] Stock Options, SARs and RSUs [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Aggregate number of shares excluded from computation of EPS Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Cross-Currency Swap 1 [Member] Cross-Currency Swap 1 [Member] Cross-Currency Swap 1 [Member] Cross-Currency Swap 2 [Member] Cross-Currency Swap 2 [Member] Cross-Currency Swap 2 [Member] Cross-Currency Swap 3 [Member] Cross-Currency Swap 3 [Member] Cross-Currency Swap 3 [Member] Cross-Currency Swap 4 [Member] Cross-Currency Swap 4 [Member] Cross-Currency Swap 4 [Member] Cross-Currency Swap 5 [Member] Cross-Currency Swap 5 [Member] Cross-Currency Swap 5 [Member] Cross-Currency Swap 6 [Member] Cross-Currency Swap 6 [Member] Cross-Currency Swap 6 [Member] Cross-Currency Swap 7 [Member] Cross-Currency Swap 7 [Member] Cross-Currency Swap 7 [Member] Cross-Currency Swap 8 [Member] Cross-Currency Swap 8 [Member] Cross-Currency Swap 8 [Member] Cross-Currency Swap 9 [Member] Cross-Currency Swap 9 [Member] Cross-Currency Swap 9 [Member] Cross-Currency Swap 10 [Member] Cross-Currency Swap 10 [Member] Cross-Currency Swap 10 [Member] Cross-Currency Swap 11 [Member] Cross-Currency Swap 11 [Member] Cross-Currency Swap 11 [Member] Cross-Currency Swap 12 [Member] Cross-Currency Swap 12 [Member] Cross-Currency Swap 12 [Member] Notional amount of derivative instruments without exchange of notional amounts at inception and maturity Notional Amount of Derivative Instruments without Exchange of Notional Amounts at Inception and Maturity Notional Amount of Derivative Instruments without Exchange of Notional Amounts at Inception and Maturity Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Loss from discontinued operations Adjustments to reconcile loss from continuing operations to net cash provided by operating activities from continuing operations: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Share-based compensation expense Share-based Compensation Impairment, restructuring and other operating items, net Amortization of deferred financing costs and non-cash interest Amortization of Debt Issuance Costs and Discounts Realized and unrealized losses on derivative instruments, net Foreign currency transaction losses (gains), net Realized and unrealized losses (gains) due to changes in fair values of certain investments and debt, net Realized and Unrealized Losses (Gains) due to Changes in Fair Values of Certain Investments and Debt Realized and Unrealized Losses (Gains) due to Changes in Fair Values of Certain Investments and Debt Losses on debt modification and extinguishment, net Deferred income tax benefit Deferred Income Tax Expense (Benefit) Changes in operating assets and liabilities, net of the effects of acquisitions and dispositions Increase (Decrease) in Operating Capital Net cash provided by operating activities of continuing operations Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash provided by operating activities of discontinued operations Cash Provided by (Used in) Operating Activities, Discontinued Operations Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Productive Assets Investments in and loans to affiliates and others Payments to Acquire Interest in Subsidiaries and Affiliates Distributions received from affiliates Proceeds from Equity Method Investment, Distribution, Return of Capital Equalization payment related to the VodafoneZiggo JV Transaction Proceeds from Collection of Advance to Affiliate Other investing activities, net Payments for (Proceeds from) Other Investing Activities Net cash provided (used) by investing activities of continuing operations Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash used by investing activities of discontinued operations Cash Provided by (Used in) Investing Activities, Discontinued Operations Net cash provided (used) by investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Repayments and repurchases of debt and capital lease obligations Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities Borrowings of debt Proceeds from Issuance of Long-term Debt Repurchase of Liberty Global ordinary shares Payment of financing costs and debt premiums Payment Of Deferred Financing Costs Debt Premiums And Exchange Offer Consideration Payment Of Deferred Financing Costs Debt Premiums And Exchange Offer Consideration Net cash received (paid) related to derivative instruments Payments for (Proceeds from) Hedge, Financing Activities Value-added taxes (VAT) paid on behalf of the VodafoneZiggo JV Other financing activities, net Proceeds from (Payments for) Other Financing Activities Net cash used by financing activities of continuing operations Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by financing activities of discontinued operations Cash Provided by (Used in) Financing Activities, Discontinued Operations Net cash used by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents and restricted cash: Effect of Exchange Rate on Cash [Abstract] Continuing operations Effect of Exchange Rate on Cash and Cash Equivalents, Continuing Operations Discontinued operations Effect of Exchange Rate on Cash and Cash Equivalents, Discontinued Operations Total Effect of Exchange Rate on Cash and Cash Equivalents Net increase (decrease) in cash and cash equivalents and restricted cash: Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Continuing operations Net Cash Provided by (Used in) Continuing Operations Discontinued operations Net Cash Provided by (Used in) Discontinued Operations Total Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents and restricted cash — continuing operations: Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Beginning of period End of period Cash paid for interest: Interest Paid [Abstract] Continuing operations Interest Paid, Continuing Operations Interest Paid, Continuing Operations Discontinued operations Interest Paid, Discontinued Operations Total Interest Paid, Net Net cash paid for taxes: Income Taxes Paid, Net [Abstract] Continuing operations Income Taxes Paid, Continuing Operations Income Taxes Paid, Continuing Operations Discontinued operations Income Taxes Paid, Discontinued Operations Income Taxes Paid, Discontinued Operations Total Income Taxes Paid, Net Summary of changes in restructuring liability Schedule of Restructuring Reserve by Type of Cost [Table Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Other, including intersegment eliminations Geography Eliminations [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] U.K. [Member] UNITED KINGDOM Switzerland [Member] SWITZERLAND Ireland [Member] IRELAND Poland [Member] POLAND Austria [Member] AUSTRIA [Member] AUSTRIA [Member] Hungary [Member] HUNGARY The Czech Republic [Member] CZECH REPUBLIC Romania [Member] ROMANIA Slovakia [Member] SLOVAKIA Equity Stockholders' Equity Note Disclosure [Text Block] Loss Contingencies [Table] Loss Contingencies [Table] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Broadband Communications and DHT Operations [Member] Broadband Communications and DHT Operations [Member] Broadband Communications and DHT Operations [Member] Loss Contingencies by Nature of Contingency [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Interkabel Acquisition [Member] Interkabel Acquisition [Member] Interkabel Acquisition [Member] Deutsche Telekom Litigation [Member] Deutsche Telekom Litigation [Member] Deutsche Telekom Litigation [Member] Virgin Media VAT Matters [Member] Virgin Media VAT Matters [Member] Virgin Media VAT Matters [Member] Virgin Media VAT Matters 2 [Member] Virgin Media VAT Matters 2 [Member] Virgin Media VAT Matters 2 [Member] Other Regulatory Issues [Member] Unfavorable Regulatory Action [Member] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Programming costs Programming and Copyright Costs Programming and Copyright Costs Estimate of possible loss Loss Contingency, Estimate of Possible Loss Number of associations of municipalities in Belgium Number of Associations of Municipalities in Belgium Number of Associations of Municipalities in Belgium Damages sought Loss Contingency, Damages Sought, Value Loss contingency damages in excess value Loss Contingency Damages In Excess Value Loss Contingency Damages In Excess Value Loss contingency accrual Loss Contingency Accrual Reduction of annual lease fees Reduction of Annual Lease Fees Reduction of Annual Lease Fees Continuing operations Income Taxes Paid Interest expense Income Tax Examination, Interest Expense Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Quoted prices in active markets for identical assets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant unobservable inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Derivative instruments Investments, fair value Total assets Assets, Fair Value Disclosure Derivative instruments Debt Instrument, Fair Value Disclosure Total liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Statement of Financial Position [Abstract] Class A ordinary shares, $0.01 nominal value. Issued and outstanding 217,547,694 and 219,668,579 shares, respectively Class B ordinary shares, $0.01 nominal value. Issued and outstanding 11,102,619 shares at each date Common Class B [Member] Class C ordinary shares, $0.01 nominal value. Issued and outstanding 572,061,952 and 584,332,055 shares, respectively ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Trade receivables, net Accounts Receivable, Net, Current Derivative instruments (note 6) Prepaid expenses Prepaid Expense, Current Current assets held for sale (note 4) Disposal Group, Including Discontinued Operation, Assets, Current Other current assets (notes 3 and 5) Other Assets, Current Total current assets Assets, Current Investments and related note receivables (including $2,288.8 million and $2,315.3 million, respectively, measured at fair value on a recurring basis) (note 5) Long-term Investments Property and equipment, net (note 8) Goodwill (note 8) Deferred tax assets (note 10) Deferred Income Tax Assets, Net Long-term assets held for sale (note 4) Disposal Group, Including Discontinued Operation, Assets, Noncurrent Other assets, net (notes 3, 6 and 8) Other Assets, Noncurrent Total assets Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Deferred revenue Deferred Revenue, Current Current portion of debt and capital lease obligations (note 9) Debt, Current Accrued capital expenditures Accrued Capital Expenditures, Current Accrued Capital Expenditures, Current Accrued interest Interest Payable, Current Accrued income taxes Accrued Income Taxes, Current Current liabilities held for sale (note 4) Disposal Group, Including Discontinued Operation, Liabilities, Current Other accrued and current liabilities (notes 6 and 13) Other Accrued Liabilities, Current Total current liabilities Liabilities, Current Long-term debt and capital lease obligations (note 9) Long-term liabilities held for sale (note 4) Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent Other long-term liabilities (notes 6, 10, and 13) Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (notes 6, 9, 10 and 15) Commitments and Contingencies Equity (note 11): Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Liberty Global shareholders: Stockholders' Equity Attributable to Parent [Abstract] Common stock Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated deficit Retained Earnings (Accumulated Deficit) Accumulated other comprehensive earnings, net of taxes Accumulated Other Comprehensive Income (Loss), Net of Tax Treasury shares, at cost Treasury Stock, Value Total Liberty Global shareholders Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Revenue Recognition and Related Costs Revenue from Contract with Customer [Text Block] Revenue and Operating Cash Flow by Segment Schedule Of Revenue and Operating Cash Flow Segment Reporting Information By Segment [Table Text Block] Segment Revenue, & OCF year over year comparison. Total Segment Operating Cash Flow to Earnings (Loss) from Continuing Operations before Income Taxes Schedule of Reconciliation of Total Segment Operating Cash Flow From Continuing Operations to Loss From Continuing Operations Before Income Taxes [Table Text Block] Schedule of Reconciliation of Total Segment Operating Cash Flow From Continuing Operations to Loss From Continuing Operations Before Income Taxes [Table Text Block] Schedule of Reporting Capital Expenditures of Reportable Segments Schedule of Reporting Capital Expenditures of Reportable Segments [Table Text Block] Schedule of Reporting Capital Expenditures of Reportable Segments [Table Text Block] Revenue by Major Category Revenue from External Customers by Products and Services [Table Text Block] Geographic Segments Revenue from External Customers by Geographic Areas [Table Text Block] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Employee severance and termination costs [Member] Employee Severance [Member] Office closures [Member] Facility Closing [Member] Contract termination and other [Member] Contract Termination and Other [Member] Contract Termination and Other [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Restructuring liability as of January 1, 2018 Restructuring Reserve Restructuring charges Restructuring Charges Cash paid Payments for Restructuring Foreign currency translation adjustments and other Restructuring Reserve, Foreign Currency Translation Gain (Loss) Restructuring liability as of March, 31, 2018 Current portion Restructuring Reserve, Current Noncurrent portion Restructuring Reserve, Noncurrent Total Fair Value Measurements Fair Value Disclosures [Text Block] Unrecorded Purchase Obligation Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Debt and Capital Lease Obligations Debt Disclosure [Text Block] Intersegment Eliminations [Member] Intersegment Eliminations [Member] Adjusted OIBDA Adjusted Operating Income (Loss) before Depreciation and Amortization Adjusted Operating Income (Loss) before Depreciation and Amortization Adjusted OIBDA Equity Method Investment, Summarized Financial Information, EBITDA Equity Method Investment, Summarized Financial Information, EBITDA Schedule of Finite-Lived Intangible Assets by Major Class [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer Relationships [Member] Customer Relationships [Member] Other [Member] Other Intangible Assets [Member] Gross carrying amount Finite-Lived Intangible Assets, Gross Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Net carrying amount Finite-Lived Intangible Assets, Net Computed “expected” tax benefit Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Mandatory Repatriation Tax Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount Change in valuation allowances: Effective Income Tax Rate Reconciliation, Change in Valuation Allowance, Amount [Abstract] Effective Income Tax Rate Reconciliation, Change in Valuation Allowance, Amount [Abstract] Benefit Effective Income Tax Rate Reconciliation, Increase in Deferred Tax Assets Valuation Allowance, Amount Effective Income Tax Rate Reconciliation, Increase in Deferred Tax Assets Valuation Allowance, Amount Expense Effective Income Tax Rate Reconciliation, Decrease in Deferred Tax Assets Valuation Allowance, Amount Effective Income Tax Rate Reconciliation, Decrease in Deferred Tax Assets Valuation Allowance, Amount Non-deductible or non-taxable foreign currency exchange results: Effective Income Tax Rate Reconciliation, Non-Deductible or Non-Taxable Foreign Currency Exchange Results, Amount [Abstract] Effective Income Tax Rate Reconciliation, Non-Deductible or Non-Taxable Foreign Currency Exchange Results, Amount [Abstract] Expense Effective Income Tax Rate Reconciliation, Decrease in Non-Deductible or Non-Taxable Foreign Currency Exchange Results, Amount Effective Income Tax Rate Reconciliation, Decrease in Non-Deductible or Non-Taxable Foreign Currency Exchange Results, Amount Benefit Effective Income Tax Rate Reconciliation, Increase in Non-Deductible or Non-Taxable Foreign Currency Exchange Results, Amount Effective Income Tax Rate Reconciliation, Increase in Non-Deductible or Non-Taxable Foreign Currency Exchange Results, Amount Non-deductible or non-taxable interest and other items Effective Income Tax Rate Reconciliation, Non-deductible or Non-Taxable Interest and Other Expenses, Amount [Abstract] Effective Income Tax Rate Reconciliation, Non-deductible or Non-Taxable Interest and Other Expenses, Amount [Abstract] Expense Effective Income Tax Rate Reconciliation, Decrease in Non-deductible or Non-Taxable Interest and Other Expenses, Amount Effective Income Tax Rate Reconciliation, Decrease in Non-deductible or Non-Taxable Interest and Other Expenses, Amount Benefit Effective Income Tax Rate Reconciliation, Increase in Non-deductible or Non-Taxable Interest and Other Expenses, Amount Effective Income Tax Rate Reconciliation, Increase in Non-deductible or Non-Taxable Interest and Other Expenses, Amount Basis and other differences in the treatment of items associated with investments in subsidiaries and affiliates: Effective Income Tax Rate Reconciliation, Basis and Other Differences in the Treatment of Items Associated with Investments in Subsidiaries and Affiliates, Amount [Abstract] Effective Income Tax Rate Reconciliation, Basis and Other Differences in the Treatment of Items Associated with Investments in Subsidiaries and Affiliates, Amount [Abstract] Decrease Effective Income Tax Rate Reconciliation, Decrease in Basis and Other Differences in the Treatment of Items Associated with Investments in Subsidiaries and Affiliates, Amount Effective Income Tax Rate Reconciliation, Decrease in Basis and Other Differences in the Treatment of Items Associated with Investments in Subsidiaries and Affiliates, Amount Increase Effective Income Tax Rate Reconciliation, Increase in Basis and Other Differences in the Treatment of Items Associated with Investments in Subsidiaries and Affiliates, Amount Effective Income Tax Rate Reconciliation, Increase in Basis and Other Differences in the Treatment of Items Associated with Investments in Subsidiaries and Affiliates, Amount International rate differences: Effective Income Tax Rate Reconciliation, International Rate Differences, Amount [Abstract] Effective Income Tax Rate Reconciliation, International Rate Differences, Amount [Abstract] Benefit Effective Income Tax Rate Reconciliation, Increase in Foreign Income Tax Rate Differential, Amount Effective Income Tax Rate Reconciliation, Increase in Foreign Income Tax Rate Differential, Amount Expense Effective Income Tax Rate Reconciliation, Decrease in Foreign Income Tax Rate Differential, Amount Effective Income Tax Rate Reconciliation, Decrease in Foreign Income Tax Rate Differential, Amount Recognition of previously unrecognized tax benefits Income Tax Reconciliation, Previously Unrecognized Tax Benefits Income Tax Reconciliation, Previously Unrecognized Tax Benefits Other, net Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount Total income tax expense Acquisitions, Disposals and Discontinued Operations Acquisitions, Disposals and Discontinued Operations [Text Block] Acquisitions, Disposals and Discontinued Operations [Text Block] Common Class B [Member] Common stock, nominal value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, issued (in shares) Common Stock, Shares, Issued Common stock, outstanding (in shares) Common Stock, Shares, Outstanding Non-cash borrowings and repayments of debt Non-Cash Borrowings and Repayments of Debt Non-Cash Borrowings and Repayments of Debt Summary of stock-based compensation Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Schedule of stock option activity Share-based Compensation, Stock Options, Activity [Table Text Block] Schedule of other share based compensation activity Schedule of Other Share-based Compensation, Activity [Table Text Block] Document and Entity Information [Abstract] Document And Entity Information [Abstract] Document and Entity Information [Table] Document and Entity Information [Table] Document and Entity Information [Table] Document and Entity Information [Line Items] Document and Entity Information [Line Items] [Line Items] for Document and Entity Information [Table] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Income Tax Benefit (Expense) Reconciliation Table Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 [Member] Accounting Standards Update 2014-09 [Member] Accounting Standards Update 2017-07 [Member] Accounting Standards Update 2017-07 [Member] Accounting Standards Update 2017-07 [Member] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Other Operating Expense [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Condensed Consolidated Balance Sheet Assets: Other current assets Investments and related note receivables Deferred tax assets Other assets, net Liabilities: Liabilities [Abstract] Other accrued and current liabilities Other long-term liabilities Equity: Reclassification to other income, net Total segment Adjusted OIBDA from continuing operations Share-based compensation expense Depreciation and amortization Impairment, restructuring and other operating items, net Realized and unrealized losses on derivative instruments, net Foreign currency transaction gains (losses), net Realized and unrealized gains (losses) due to changes in fair values of certain investments and debt, net Losses on debt modification and extinguishment, net Share of losses of affiliates, net Loss from continuing operations before income taxes Income (loss) from continuing operations before income taxes Sum of operating profit and nonoperating income (expense) before income taxes. Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Total Liberty Global shareholders Parent [Member] Additional paid-in capital [Member] Additional Paid-in Capital [Member] Accumulated deficit [Member] Retained Earnings [Member] Accumulated other comprehensive earnings (loss), net of taxes [Member] AOCI Attributable to Parent [Member] Treasury shares, at cost [Member] Treasury Stock [Member] Non-controlling interests [Member] Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance at January 1, 2018, before effect of accounting change Accounting change (note 2) Cumulative Effect of New Accounting Principle in Period of Adoption Balance at January 1, 2018, as adjusted for accounting change Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance Net loss Other comprehensive earnings, net of taxes Repurchase and cancellation of Liberty Global ordinary shares (note 11) Stock Repurchased and Retired During Period, Value Share-based compensation (note 12) Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Adjustments due to changes in subsidiaries’ equity and other, net Stockholders' Equity, Other Balance at March 31, 2018 Principal Transaction Revenue [Table] Principal Transaction Revenue [Table] Cable [Member] Cable [Member] Cable [Member] Cable Subscription [Member] Cable Subscription [Member] Cable Subscription [Member] Cable Video Subscription [Member] Cable Video Subscription [Member] Cable Video Subscription [Member] Cable Broadband Internet Subscription [Member] Cable Broadband Internet Subscription [Member] Cable Broadband Internet Subscription [Member] Cable Fixed-line Telephony Subscription [Member] Cable Fixed-line Telephony Subscription [Member] Cable Fixed-line Telephony Subscription [Member] Cable Non-Subscription [Member] Cable Non-Subscription [Member] Cable Non-Subscription [Member] Residential [Member] Residential [Member] Residential [Member] Mobile Subscription [Member] Mobile Subscription [Member] Mobile Subscription [Member] Mobile Non-Subscription [Member] Mobile Non-Subscription [Member] Mobile Non-Subscription [Member] Mobile Residential [Member] Mobile Residential [Member] Mobile Residential [Member] Business to Business Subscription [Member] Business to Business Subscription [Member] Business to Business Subscription [Member] Business to Business Non-Subscription [Member] Business to Business Non-Subscription [Member] Business to Business Non-Subscription [Member] Other Category [Member] Other Category [Member] Other Category [Member] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] UPC Austria [Member] UPC Austria [Member] UPC Austria [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Disposal Group, Held-for-sale, Not Discontinued Operations [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Consideration for disposal Disposal Group, Including Discontinued Operation, Consideration Term of transitional services Disposal Group, Term of Transitional Services Disposal Group, Term of Transitional Services Term of brand transitional period Disposal Group, Term of Brand Transitional Period Disposal Group, Term of Brand Transitional Period Assets: Disposal Group, Including Discontinued Operation, Assets [Abstract] Current assets other than cash Disposal Group, Including Discontinued Operation, Other Assets, Current Property and equipment, net Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Noncurrent Goodwill Disposal Group, Including Discontinued Operation, Goodwill, Noncurrent Other assets, net Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent Total assets Disposal Group, Including Discontinued Operation, Assets Liabilities: Disposal Group, Including Discontinued Operation, Liabilities [Abstract] Current portion of debt and capital lease obligations Disposal Group, Including Discontinued Operation, Debt and Capital Lease Obligations, Current Disposal Group, Including Discontinued Operation, Debt and Capital Lease Obligations, Current Other accrued and current liabilities Disposal Group, Including Discontinued Operation, Accounts Payable and Accrued Liabilities, Current Other long-term liabilities Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent Total liabilities Disposal Group, Including Discontinued Operation, Liabilities Net loss Income (Loss) from Individually Significant Component Disposed of or Held-for-sale, Excluding Discontinued Operations, Attributable to Parent, before Income Tax Basis of Presentation [Table] Basis of Presentation [Table] Basis of Presentation [Table] Video, Broadband Internet and FIxed-Line Telephony, Mobile and other Communications Services [Member] Video, Broadband Internet and FIxed-Line Telephony, Mobile and other Communications Services [Member] Video, Broadband Internet and FIxed-Line Telephony, Mobile and other Communications Services [Member] Consumer and Business-to-Business Communication Services [Member] Consumer and Business-to-Business Communication Services [Member] Consumer and Business-to-Business Communication Services [Member] Sub-Sea Networks [Member] Sub-Sea Networks [Member] Sub-Sea Networks [Member] Europe [Member] Europe [Member] Latin America and the Caribbean [Member] Latin America and the Caribbean [Member] Latin America and the Caribbean [Member] Cable & Wireless Communications Limited (C&W) [Member] Cable & Wireless Communications Limited (CWC) [Member] Cable & Wireless Communications Limited (CWC) [Member] Basis of Presentation [Line Items] Basis of Presentation [Line Items] [Line Items] for Basis of Presentation [Table] Number of countries in which entity provides services Number of Countries in which Entity Operates Percentage ownership in subsidiary Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Number of markets Number of Markets Number of Markets Threshold percentage used to determine reportable segments using one of three criteria of revenue, operating cash flow or total assets Threshold Percentage Of Revenue Operating Cash Flows Or Total Assets Used To Identify Reportable Segments Threshold Percentage Of Revenue Operating Cash Flows Or Total Assets Used To Identify Reportable Segments. Performance measures, percentage of reportable segment revenue and operating cash flow presented Performance Measures Percentage Of Reportable Segment Revenue And Operating Cash Flow Presented Performance Measures Percentage Of Reportable Segment Revenue And Operating Cash Flow Presented Percentage of minority interest revenues and expenses included in net earnings attributable to noncontrolling interest Percentage Of Minority Interest Revenues And Expenses From Consolidated Statements Of Operations Included In Net Earnings Attributable To Noncontrolling Interest Percentage Of Minority Interest Revenues And Expenses From Consolidated Statements Of Operations Included In Net Earnings Attributable To Noncontrolling Interest Schedule of summarized financial position and operating results, disposal group and discontinued operations Disposal Groups, Including Discontinued Operations [Table Text Block] LiLAC Group [Member] LiLAC Group [Member] LiLAC Group [Member] Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member] Common shares distributed Disposal Group, Including Discontinued Operations, Common Share Distribution Disposal Group, Including Discontinued Operations, Common Share Distribution Gain (loss) on discontinued operation Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax Operating results of discontinued operations Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract] Revenue Disposal Group, Including Discontinued Operation, Revenue Operating income (loss) Disposal Group, Including Discontinued Operation, Operating Income (Loss) Earnings (loss) before income taxes and noncontrolling interests Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax Income tax expense Discontinued Operation, Tax Effect of Discontinued Operation Net (earnings) loss attributable to noncontrolling interests Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest Net earnings (loss) attributable to Liberty Global shareholders, net of taxes, attributable to holders of: Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Basic and diluted earnings (loss) attributable to Liberty Global shareholders per share: Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic and Diluted Share Weighted average ordinary shares outstanding - basic and diluted (in shares) Discontinued Operation, Weighted Average Number of Shares Outstanding, Basic and Diluted Discontinued Operation, Weighted Average Number of Shares Outstanding, Basic and Diluted