Stockholders' Deficit (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Jan. 30, 2015	Sep. 30, 2015	Sep. 30, 2015
Treasury Stock Repurchase Programs [Line Items]
Additional share repurchase amount authorized	$ 452.9
Remaining common stock available for repurchase	$ 547.1	$ 604.6	$ 604.6
Common stock, held in treasury		211.1	211.1
Common stock repurchased		$ 7,200.0	$ 7,200.0
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		2.3	7.5
Average stock price		$ 67.45	$ 62.88
Aggregate cost of share		$ 156.0	$ 471.8
Restricted Stock Units [Member]
Treasury Stock Repurchase Programs [Line Items]
Common stock repurchase, share			0.3
Average stock price			$ 63.70
Aggregate cost of share			$ 20.8