Share Repurchase Programs and Dividends - Share Repurchase Programs (Detail) $ / shares in Units, shares in Millions	3 Months Ended	21 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares	Mar. 31, 2016 USD ($) $ / shares shares
Equity, Class of Treasury Stock [Line Items]
Stock repurchase programs, authorized amount	$ 7,000,000,000	$ 7,000,000,000
Stock repurchase programs, remaining authorized amount	$ 853,000,000	$ 853,000,000
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased (in shares) | shares	39.3	147.9
Aggregate stock repurchase price	$ 1,600,000,000	$ 6,100,000,000
Average cost per share (in dollars per share) | $ / shares	$ 39.76	$ 41.57