Stock-Based Compensation - Summary of Stock Option Plan Activity (Detail) - Time Based and Performance Based - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options, Outstanding beginning	10,549,178	14,527,460	17,096,761
Number of Options, Granted	1,643,144	1,609,170	2,448,100
Number of Options, Forfeited	(577,618)	(1,808,315)	(798,279)
Number of Options, Exercised	(3,456,536)	(3,779,137)	(4,219,122)
Number of Options, Outstanding ending	8,158,168	10,549,178	14,527,460	17,096,761
Number of Options, Exercisable	4,319,125
Weighted-Average Exercise Price, Outstanding beginning	$ 33.96	$ 28.80	$ 25.78
Weighted-Average Exercise Price, Granted	53.99	48.24	42.01
Weighted-Average Exercise Price, Forfeited	(33.51)	(30.59)	(29.57)
Weighted-Average Exercise Price, Exercised	(28.85)	(21.84)	(24.08)
Weighted-Average Exercise Price, Outstanding ending	40.19	$ 33.96	$ 28.80	$ 25.78
Weighted-Average Exercise Price, Exercisable	$ 32.92
Weighted Average Remaining Contractual Term in Years, Outstanding Beginning	4 years 5 months 5 days	4 years 1 month 28 days	4 years 3 months 15 days	4 years 7 months 10 days
Weighted Average Remaining Contractual Term in Years, Exercisable Ending	3 years 2 months 5 days
Aggregate Intrinsic, Outstanding Beginning	$ 136	$ 231	$ 344
Aggregate Intrinsic, Outstanding Ending	43	$ 136	$ 231	$ 344
Aggregate Intrinsic, Exercisable	$ 41