Share Repurchase Programs and Dividends - Share Repurchase Programs (Detail) $ / shares in Units, shares in Millions	3 Months Ended	6 Months Ended	24 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) $ / shares shares
Equity, Class of Treasury Stock [Line Items]
Stock repurchase programs, authorized amount	$ 9,000,000,000	$ 9,000,000,000	$ 9,000,000,000
Stock repurchase programs, remaining authorized amount	$ 1,200,000,000	$ 1,200,000,000	$ 1,200,000,000
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased (in shares) | shares	50.2	89.5	198.1
Aggregate stock repurchase price	$ 1,700,000,000	$ 3,200,000,000	$ 7,800,000,000
Average cost per share (in dollars per share) | $ / shares	$ 33.55	$ 36.28	$ 39.54