Stockholders' Equity - Schedule of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding at December 31, 2018 | shares	583
Number of Shares, Exercised | shares	(95)
Number of Shares, Forfeited | shares	(18)
Number of Shares, Outstanding at June 30, 2019 | shares	470
Number of Shares, Exercisable at June 30, 2019 | shares	404
Number of Shares, Vested and expected to vest at June 30, 2019 | shares	470
Weighted - Average Exercise Price Per Share, Outstanding, Beginning balance | $ / shares	$ 35.27
Weighted - Average Exercise Price Per Share, Exercised | $ / shares	34.31
Weighted - Average Exercise Price Per Share, Forfeited | $ / shares	35.46
Weighted - Average Exercise Price Per Share, Outstanding, Ending balance | $ / shares	35.46
Weighted - Average Exercise Price Per Share, Exercisable at June 30, 2019 | $ / shares	35.67
Weighted - Average Exercise Price Per Share, Vested and expected to vest at June 30, 2019 | $ / shares	$ 35.46
Weighted - Average Remaining Contractual Term, Outstanding at June 30, 2019	4 years 7 months 13 days
Weighted - Average Remaining Contractual Term, Exercisable at June 30, 2019	4 years 4 months 2 days
Weighted - Average Remaining Contractual Term, Vested and expected to vest at June 30, 2019	4 years 7 months 13 days
Aggregate Intrinsic Value, Outstanding at June 30, 2019 | $	$ 5,433
Aggregate Intrinsic Value, Exercisable at June 30, 2019 | $	4,589
Aggregate Intrinsic Value, Vested and expected to vest at June 30, 2019 | $	$ 5,433