Share Repurchase Program (Details) - USD ($) shares in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Jan. 28, 2016	Dec. 11, 2015	Dec. 15, 2014
December 11, 2015
Equity, Class of Treasury Stock [Line Items]
Accelerated share repurchases agreement amount					$ 725,000,000.0
Percent of notional amount received in shares					80.00%
Accelerated share repurchases number of shares repurchased (in shares)				1.4	6.2
Accelerated share repurchases, settlement (payment) or receipt			$ 580,000,000
Transfer of shares to treasury stock value			$ 145,000,000
Percent of notional amount in shares to be received at end of program					20.00%
Repurchase Program 2014
Equity, Class of Treasury Stock [Line Items]
Maximum authorization under share repurchase program						$ 10,000,000,000
Remaining authorized repurchase amount	$ 3,700,000,000	$ 3,700,000,000
Repurchase of common stock (in shares)		41.0
Value of stock repurchased in the period		$ 4,000,000,000
Repurchase Program 2013
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock (in shares)	18.5
Value of stock repurchased in the period	$ 1,900,000,000