Stock-Based Compensation - Summary of Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning Balance, Shares | shares	101,084
Granted, Shares | shares	58,024
Cancelled, Shares | shares	(3,810)
Exercised, Shares | shares	(32,751)
Ending Balance, Shares | shares	122,547
Options Exercisable, Shares | shares	22,520
Beginning Balance, Weighted Average Exercise Price | $ / shares	$ 29.52
Granted, Weighted Average Exercise Price | $ / shares	78.58
Cancelled, Weighted Average Exercise Price | $ / shares	56.72
Exercised, Weighted Average Exercise Price | $ / shares	7.69
Ending Balance, Weighted Average Exercise Price | $ / shares	57.74
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 31.07
Ending Balance, Weighted Average Remaining Terms (years)	3 years 9 months 18 days
Options Exercisable, Weighted Average Remaining Terms (years)	2 years 9 months 18 days
Ending Balance, Aggregate Intrinsic Value | $	$ 2,098,758
Options Exercisable, Aggregate Intrinsic Value | $	$ 913,128