Employee Stock-based Compensation Plans - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Shares Under Option
Outstanding at beginning of period (in shares)	4,148
Granted (in shares)	0
Exercised (in shares)	(916)
Canceled (in shares)	(660)
Forfeited (in shares)	(68)
Outstanding at end of period (in shares)	2,504	4,148
Fully vested and expected to vest at period end (in shares)	2,504
Exercisable at period end (in shares)	2,352
Weighted- Average Exercise Price per Share
Outstanding at beginning of period (in usd per share)	$ 40.34
Granted (in usd per share)	0
Exercised (in usd per share)	35.50
Canceled (in usd per share)	47.71
Forfeited (in usd per share)	28.78
Outstanding at end of period (in usd per share)	40.49	$ 40.34
Fully vested and expected to vest at period end (in usd per share)	40.49
Exercisable at period end (in usd per share)	$ 41.28
Weighted- Average Remaining Contractual Term (in years)
Weighted-average remaining contractual term (in years)	3 years 8 months 12 days	3 years 9 months 18 days
Fully vested and expected to vest at period end (in years)	3 years 8 months 12 days
Exercisable at period end (in years)	3 years 6 months
Aggregate Intrinsic Value (in millions)
Aggregate Intrinsic Value	$ 0	$ 15
Fully vested and expected to vest at period end	0
Exercisable at period end	$ 0