Stockholders' Equity, Other (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			177 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Nov. 06, 2013	Feb. 05, 2013
Stock Repurchase Program [Abstract]
Incremental Class A shares authorized to buyback				$ 9
Incremental shares authorized to buyback (in shares)		800,000	500,000		500,000	500,000
Shares repurchased (in shares)	229,228	1,138,313	450,966	8,711,593
Treasury Stock, Shares, Acquired		717,389
Shares lapsed (in shares)		82,611
Average price per share of repurchased shares (in dollars per share)	$ 64.41	$ 48.25	$ 45.24	$ 42.25
Share available under program to repurchase (in shares)	923,215			923,215
Treasury Stock Acquired, Value				368.1
Dividends Payable [Line Items]
Dividends paid (in dollars per share)	$ 0.72	$ 2.88	$ 1.15
Dividend cost	18.7	76.4	30.8
Share based compensation dividends accrued	0.3	0		0.3
Debt Instrument [Line Items]
Amount available for issuance under shelf registration agreement		$ 400