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