Equity, Stock Repurchase Activities (Details) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jul. 31, 2015	Oct. 31, 2014	Feb. 28, 2014
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount							$ 2,100,000,000
Stock repurchased for tax withholding (in shares)	0.1	0.1	0.4	0.2
Stock repurchased for tax withholdings (in dollars per share)	$ 23.31	$ 25.91	$ 24.64	$ 24.80
Value of shares repurchased for tax withholding	$ 1,200,000	$ 2,300,000	$ 9,600,000	$ 4,700,000
2014 Stock Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount					$ 3,900,000,000		$ 1,200,000,000
Additional amount authorized under Stock Repurchase Plan					$ 500,000,000	$ 1,300,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 332,100,000		$ 332,100,000
Stock repurchased and retired (in shares)	5.5	23.2	8.6	40.6
Common stock repurchased under stock repurchase program average purchase price (in dollars per share)	$ 23.08	$ 25.83	$ 23.37	$ 24.64
Common stock repurchased and retired under stock repurchase program, value	$ 125,500,000	$ 600,000,000	$ 200,500,000	$ 1,000,000,000