Stockholders' Equity (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stockholders' Equity Note [Abstract]
Cash dividends declared	$ 0	$ 0	$ 0	$ 0
Value of common stock repurchased			$ 129.8	$ 70.8
Authorized stock repurchase (in shares)	75.0		75.0
Remaining shares of common stock available for purchase (in shares)	10.5		10.5