Stockholders' Deficit (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Jan. 30, 2015	Jun. 30, 2015	Jun. 30, 2015
Treasury Stock Repurchase Programs [Line Items]
Additional share repurchase amount authorized	$ 452.9
Remaining common stock available for repurchase	$ 547.1	$ 760.6	$ 760.6
Common stock, held in treasury		208.8	208.8
Common stock repurchased		$ 7,100.0	$ 7,100.0
Share Buyback Program [Member]
Treasury Stock Repurchase Programs [Line Items]
Common stock authorized to repurchase		$ 1,000.0	$ 1,000.0
Common stock repurchase, share		2.5	5.2
Average stock price		$ 63.65	$ 60.84
Aggregate cost of share		$ 156.0	$ 315.7
Restricted Stock Units [Member]
Treasury Stock Repurchase Programs [Line Items]
Common stock repurchase, share			0.3
Average stock price			$ 63.55
Aggregate cost of share			$ 20.1