Document Information [Table] Legal Entity [Axis] Entity [Domain] Class of Stock [Axis] Class of Stock [Domain] Common Class A [Member] Preferred Stock Purchase Rights [Member] Preferred stock purchase rights securities registered pursuant to section 12(b). Common Class B [Member] Depository Shares [Member] Depository shares registered pursuant to section 12(b). Document Information [Line Items] Entity, Registrant Name Document, Type Document, Period End Date Entity, Incorporation, State or Country Code Entity, File Number Entity, Tax Identification Number Entity, Address, Address Line One 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 No Trading Symbol Flag Security Exchange Name Entity, Emerging Growth Company Amendment Flag Entity, Central Index Key