Stock-Based Awards - Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Shares
Beginning balance (in shares) | shares	3,828
Options, Granted (in shares) | shares	0
Options, Exercised (in shares) | shares	(270)
Options, Forfeited (in shares) | shares	(32)
Ending balance (in shares) | shares	3,526	3,828
Weighted- Average Exercise Price
Weighted-average exercise price, outstanding at beginning of period (USD per share)	$ 32.41
Weighted average exercise price, granted (USD per share)	0
Weighted average exercise price, exercised (USD per share)	37.59
Weighted average exercise price, forfeited (USD per share)	47.50
Weighted-average exercise price, outstanding at end of period (USD per share)	$ 31.88	$ 32.41
Additional Disclosures
Weighted-average remaining contractual term, outstanding	3 years 7 months 6 days	4 years 1 month 6 days
Aggregate intrinsic value, outstanding | $	$ 91,853	$ 70,436
Exercisable at end of period (in shares) | shares	3,511
Weighted average exercise price, exercisable at end of period (USD per share)	$ 31.87
Weighted-average remaining contractual term, exercisable	3 years 7 months 6 days
Aggregate intrinsic value, exercisable at end of period | $	$ 91,494
Vested and Expected to Vest
Vested and expected to vest at end of period (in shares) | shares	3,526
Weighted average exercise price, vested and expected to vest at end of period (USD per share)	$ 31.88
Weighted-average remaining contractual term, vested and expected to vest	3 years 7 months 6 days
Aggregate intrinsic value, vested and expected to vest at end of period | $	$ 91,839
Closing stock price (USD per share)	$ 57.93	$ 50.43