Stockholders' Deficit (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 11, 2016	Jun. 30, 2016	Jun. 30, 2016
Treasury Stock Repurchase Programs [Line Items]
Additional share repurchase amount authorized	$ 611.2
Remaining common stock available for repurchase	$ 388.8	$ 765.9	$ 765.9
Common stock, held in treasury		216.8	216.8
Common stock repurchased		$ 7,800.0	$ 7,800.0
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		1.7	3.5
Average stock price		$ 86.46	$ 84.63
Aggregate cost of share		$ 149.9	$ 299.8
Restricted Stock Units [Member]
Treasury Stock Repurchase Programs [Line Items]
Common stock repurchase, share			0.3
Average stock price			$ 80.92
Aggregate cost of share			$ 24.4