Treasury Stock (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount	$ 6,300,000,000		$ 6,300,000,000
Available to repurchase common stock	404,000,000		404,000,000
Amount expended on share repurchases in open market transactions	0	$ 279,500,000	$ 28,700,000	$ 451,600,000
Number of shares repurchased		3,895,283	426,300	6,588,783
Average per share price on share repurchases in open market transactions (in dollars per share)		$ 71.75	$ 67.30	$ 68.54
Shares repurchased, not yet settled	$ 53,600,000		$ 53,600,000
Number of shares withheld to satisfy minimum tax withholding obligations	134,782	55,963	698,391	501,785
Payment for tax withholding related to vested stock units	$ 12,000,000	$ 4,100,000	$ 55,000,000	$ 32,400,000
Amount Authorized in January 2016 [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount	$ 400,000,000		$ 400,000,000