Share Repurchase Programs and Dividends - Share Repurchase Programs (Detail) - USD ($)	12 Months Ended			30 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Jan. 31, 2017
Equity, Class of Treasury Stock [Line Items]
Stock repurchase programs, authorized amount	$ 9,000,000,000			$ 9,000,000,000
Stock repurchase programs, remaining authorized amount	$ 0			$ 0
Stock repurchased (in shares)	119,823,621	85,141,691	23,406,472	228,400,000
Aggregate stock repurchase price	$ 4,416,000,000	$ 3,586,000,000	$ 1,000,000,000	$ 9,000,000,000
Average cost per share (in dollars per share)	$ 36.86	$ 42.09	$ 42.72	$ 39.41
Subsequent Event [Member] | Share Repurchase Program January 2017 [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase programs, authorized amount					$ 2,000,000,000