Stockholders' Equity - Schedule of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding at December 31, 2017 | shares	937
Number of Shares, Exercised | shares	(50)
Number of Shares, Forfeited | shares	(12)
Number of Shares, Outstanding at March 31, 2018 | shares	875
Number of Shares, Exercisable at March 31, 2018 | shares	625
Number of Shares, Vested and expected to vest at March 31, 2018 | shares	875
Weighted - Average Exercise Price Per Share, Outstanding, Beginning balance | $ / shares	$ 35.10
Weighted - Average Exercise Price Per Share, Exercised | $ / shares	33.31
Weighted - Average Exercise Price Per Share, Forfeited | $ / shares	35.02
Weighted - Average Exercise Price Per Share, Outstanding, Ending balance | $ / shares	35.21
Weighted - Average Exercise Price Per Share, Exercisable at March 31, 2018 | $ / shares	35.17
Weighted - Average Exercise Price Per Share, Vested and expected to vest at March 31, 2018 | $ / shares	$ 35.21
Weighted - Average Remaining Contractual Term, Outstanding at March 31, 2018	5 years 9 months
Weighted - Average Remaining Contractual Term, Exercisable at March 31, 2018	5 years 1 month 28 days
Weighted - Average Remaining Contractual Term, Vested and expected to vest at March 31, 2018	5 years 9 months
Aggregate Intrinsic Value, Outstanding at March 31, 2018 | $	$ 5,465
Aggregate Intrinsic Value, Exercisable at March 31, 2018 | $	3,924
Aggregate Intrinsic Value, Vested and expected to vest at March 31, 2018 | $	$ 5,465