Share Repurchase Plan - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	5 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	May 31, 2014	Mar. 31, 2013
Equity [Abstract]
Repurchase of outstanding common stock				$ 6,500,000,000	$ 4,000,000,000
Number of shares purchased	19.3	43.4	19.3
Shares purchased value	1,500,000,000	3,722,000,000	1,538,000,000
Average cost per share of share repurchased	$ 79.65	$ 85.83
Additional amount of common stock that may be repurchased under this board authorized plan		$ 1,240,000,000