Equity (parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Common Stock Number Of Shares Par Value And Other Disclosures Abstract
Common Stock Par Value Per Share	$ 0.01	$ 0.01
Class A Common Stock
Class Of Stock [Line Items]
Common Stock Shares Authorized	50.0	50.0
Common Stock Shares Outstanding	7.2	7.2
Class B Common Stock
Class Of Stock [Line Items]
Common Stock Shares Authorized	150.0	150.0
Common Stock Shares Outstanding	52.2	52.1