Share-based Compensation - Schedule of Stock Option Plans (Detail)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at the beginning of the period (in shares) | shares	1,086,822
Granted | shares	231,548
Exercised | shares	(100,821)
Forfeited | shares	(41,662)
Outstanding at the end of the period (in shares) | shares	1,175,887
Vested and expected to vest | shares	1,175,887
Exercisable (in shares) | shares	696,248
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 37.47
Granted | $ / shares	57.66
Exercised | $ / shares	27.80
Forfeited | $ / shares	48.80
Outstanding at the end of the period (in dollars per share) | $ / shares	41.87
Vested and expected to vest | $ / shares	41.87
Exercisable | $ / shares	$ 36.67
Options outstanding, weighted average remaining contractual term	6 years 7 months 9 days
Options vested and expected, weighted average remaining contractual term	6 years 7 months 9 days
Options exercisable, weighted average remaining contractual term	5 years 4 months 9 days