Share Repurchase Programs - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			1 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended	2 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Aug. 09, 2011 Share repurchase program, August 2010 - August 2011	May 31, 2011 Share repurchase program, August 2010 - August 2011	Dec. 31, 2013 Share repurchase program, August 2010 - August 2011		May 31, 2011 Share Repurchase Program May 2011	Dec. 31, 2013 Share Repurchase Program May 2011	Feb. 24, 2012 Share repurchase program, August 2011 - February 2012	Feb. 29, 2012 Share repurchase program, August 2011 - February 2012	Dec. 31, 2013 Share repurchase program, August 2011 - February 2012	Jan. 30, 2013 Share repurchase program, August 2012 - January 2013	Jan. 31, 2013 Share repurchase program, August 2012 - January 2013	Dec. 31, 2013 Share repurchase program, August 2012 - January 2013	May 21, 2013 Share repurchase program, August 2012 - January 2013	Mar. 12, 2013 Share repurchase program, August 2012 - January 2013 Maximum	Dec. 31, 2013 Share repurchases under 2013 program
Equity, Class of Treasury Stock [Line Items]
Amount authorized for repurchase of outstanding common stock	$ 5,300			$ 1,400	$ 1,000	$ 1,400	[1]			$ 750		$ 750	$ 500		$ 500		$ 500
Authorized amount for additional repurchase of outstanding common stock								400								500
Payments for repurchase of common stock	795	578	1,586					1,400
Repurchase of common stock, shares	160.8					45.1	[1]		45.1		4.9	20.1		2.8	12.7			15.2
Average per share price of repurchase of common stock									$ 31.02		$ 38.28	$ 37.29		$ 39.24	$ 39.38			$ 45.14
Repurchase of common stock	$ 795	$ 578	$ 1,586								$ 188			$ 109				$ 686

[1] As amended on May 19, 2011