Shareholders' Equity (Deficit) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity [Abstract]
Authorized shares	300,000,000	300,000,000
Par value of common stock (in dollars per share)	$ 0.01	$ 0.01
Shares reserved for issuance of stock options	800,000
Stock Issued During Period, Value, Stock Options Exercised	$ 34.4	$ 32.2	$ 12.1
Common stock activity roll forward
Common stock outstanding at the beginning of the period (in shares)	75,565,409	73,886,050
Stock options exercised (in shares)	1,464,294	1,679,359	765,693
Common stock outstanding at the end of the period (in shares)	77,046,143	75,565,409	73,886,050
Common Stock, Shares, Issued	10,440
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	6,000
Shares, Issued	16,440