Stock Options Status and Activity (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Jun. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, Beginning Balance	2,086,770	2,119,003	1,983,573		1,983,573
Granted	834		192,624	0
Canceled	(526)		(31,299)
Forfeited	(1,535)		(300)	0
Exercised	(12,358)	(32,233)	(25,595)
Outstanding, Ending Balance	2,073,185	2,086,770	2,119,003		2,086,770		1,983,573
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, Beginning Balance	$ 26.11	$ 26.10	$ 22.93		$ 22.93
Granted	$ 66.54		$ 56.23	$ 0.00
Canceled	$ 36.00		$ 19.78
Forfeited	$ 29.72		$ 22.77	$ 0.00
Exercised	$ 23.81	$ 25.49	$ 14.72
Outstanding, Ending Balance	$ 26.13	$ 26.11	$ 26.10		$ 26.11		$ 22.93
Weighted Avg. Remaining Life in Years			4 years 7 months 5 days		4 years 3 months 17 days	4 years 1 month 5 days	4 years 6 months 0 days
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 75	$ 67	$ 62		$ 62
Aggregate Intrinsic Value, Exercised	1		1
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 77	$ 75	$ 67		$ 75		$ 62