Earnings Per Share (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net income	$ 998	$ 916	$ 891	$ 953	$ 765	$ 640	$ 328	$ 973	$ 3,758	$ 2,706	$ 1,540
Weighted-average shares outstanding									340,906,490	339,843,438	338,159,409
Share-based compensation plans									3,241,085	2,903,512	2,620,815
Adjusted weighted-average shares outstanding and assumed conversions									344,147,575	342,746,950	340,780,224
Basic earnings per share	$ 2.93	$ 2.68	$ 2.61	$ 2.80	$ 2.24	$ 1.88	$ 0.96	$ 2.87	$ 11.02	$ 7.96	$ 4.55
Diluted earnings per share	$ 2.90	$ 2.66	$ 2.59	$ 2.77	$ 2.22	$ 1.86	$ 0.96	$ 2.84	$ 10.92	$ 7.89	$ 4.52
Potential anti-dilutive share conversions									1,031,297	896,591	111,326