Share Repurchase Program (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended					1 Months Ended		12 Months Ended		1 Months Ended	2 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 Share repurchase program, July 2008 - October 2008	Dec. 31, 2013 Share repurchase programs, May 2009 - July 2009	Dec. 31, 2013 Share repurchase program, July 2009 - January 2010	Dec. 31, 2013 Share repurchase program, February 2010 - May 2010	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		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	Dec. 31, 2013 Share Repurchase Program March, 2013
Equity, Class of Treasury Stock [Line Items]
Amount authorized	$ 5,300	$ 400	$ 250	$ 750	$ 250	$ 1,400	$ 1,000	$ 1,400	[1]	$ 750		$ 750	$ 500		$ 500	$ 1,000	[2]
Number of shares repurchased	160.8	17.6	11.0	29.3	9.8			45.1	[1]		4.9	20.1		2.8	12.7	15.2	[2]
Share repurchase program periods		July 2008 - October 2008	May 2009 - July 2009	July 2009 - January 2010	February 2010 - May 2010			August 2010 - August 2011	[1]			August 2011 - February 2012			August 2012 - January 2013	March 2013	[2]

[1] As amended on May 19, 2011

[2] As amended on May 21, 2013