Stock Options Status and Activity (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, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Under Option Outstanding Beginning Balance	2,113,889	2,260,743	2,654,247	2,447,475	2,447,475
Shares Under Option, Granted	0	1,182	388	311,539
Share Under Option, Canceled	0			(7,225)
Shares Under Option, Forfeited	0	(283)	(450)	(14,920)
Shares Under Option, Exercised	(130,316)	(147,753)	(393,442)	(82,622)
Shares Under Option Outstanding Ending Balance	1,983,573	2,113,889	2,260,743	2,654,247	1,983,573	2,447,475
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Prices, Outstanding, Beginning Balance	$ 22.52	$ 22.06	$ 22.12	$ 20.14	$ 20.14
Weighted Average Exercise Prices, Granted	$ 0	$ 35.41	$ 38.90	$ 36.29
Weighted Average Exercise Price, Canceled	$ 0.00			$ 11.73
Weighted Average Exercise Prices, Forfeited	$ 0.00	$ 8.68	$ 21.81	$ 14.59
Weighted Average Exercise Prices, Exercised	$ 16.23	$ 15.42	$ 22.53	$ 19.96
Weighted Average Exercise Prices, Outstanding, Ending Balance	$ 22.93	$ 22.52	$ 22.06	$ 22.12	$ 22.93	$ 20.14
Weighted Average Remaining Life in Years	4 years 6 months	4 years 7 months 6 days	4 years 8 months 12 days	4 years 3 months 18 days		4 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 56	$ 44	$ 41	$ 29	$ 29
Aggregate Intrinsic Value, Exercised	5	0	7	1	19	10	13
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 62	$ 56	$ 44	$ 41	$ 62	$ 29