Equity and Comprehensive Income - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Nov. 28, 2012	Feb. 17, 2013	Feb. 12, 2012	Feb. 17, 2013	Feb. 12, 2012	Dec. 18, 2012
Equity And Comprehensive Income [Line Items]
Dividends declared and paid		$ 0.275	$ 0.240
Special cash dividend declared and paid, per share	$ 7.00	$ 7.00		$ 7.00
Special dividend paid						$ 3,049
Special cash dividend declared, declared date	Nov. 28, 2012
Special cash dividend declared, payable date	Dec. 18, 2012
Special cash dividend declared, record date	Dec. 10, 2012
Shares repurchased			1,759,000	357,000	3,881,000
Average price per share			$ 82.20	$ 96.41	$ 81.84
Total cost			145	34	318
Stock repurchase authorization amount remaining				$ 3,055