Total Equity Equity II (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Class Of Stock [Line Items]
Common stock par value per share (USD 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, issued	7.2	7.2
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, issued	50.7	51.3
Common stock, shares outstanding	50.7	51.3