Cover page. Entities [Table] Entities [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Class A [Member] Common Class A [Member] Common Class B [Member] Common Class B [Member] Common Class C [Member] Common Class C [Member] Entity Information [Line Items] Entity Information [Line Items] Document Type Document Type Document Period End Date Document Period End Date Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Amendment Flag Amendment Flag Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity File Number Entity File Number Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, Country Entity Address, Country Entity Address, Postal Zip Code Entity Address, Postal Zip Code Country Region Country Region City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Written Communications Written Communications Soliciting Material Soliciting Material Pre-commencement Tender Offer Pre-commencement Tender Offer Pre-commencement Issuer Tender Offer Pre-commencement Issuer Tender Offer Entity Emerging Growth Company Entity Emerging Growth Company