Stock Incentive Plans - Summary of Option, Unvested RSU Activity under 2014 Equity Incentive Plan and 2016 Inducement Equity Incentive Plan and Related Information (Detail)	9 Months Ended
	Sep. 30, 2021 $ / shares shares
Shares Available for Grant
Shares available for grant beginning balance (in shares)	672,968
Additional options authorized (in shares)	1,977,647
Common stock awards for services (in shares)	(2,998)
RSUs granted (in shares)	(797,290)
Options granted (in shares)	(187,514)
Repurchase of common stock under employee incentive plans (in shares)	216,813
RSUs forfeited (in shares)	226,564
Options forfeited (in shares)	214,115
Options expired (in shares)	7,787
Shares available for grant ending balance (in shares)	2,328,092
Stock Options Outstanding
Stock options outstanding beginning balance (in shares)	2,670,398
Stock options granted (in shares)	187,514
Stock option exercised (in shares)	(646,724)
Stock options forfeited (in shares)	(214,115)
Stock options expired (in shares)	(7,787)
Stock options outstanding ending balance (in shares)	1,989,286
Weighted- Average Exercise Price
Weighted average exercise price beginning balance (in dollars per share) | $ / shares	$ 21.92
Weighted average exercise price - options granted (in dollars per share) | $ / shares	80.40
Weighted average exercise price - options exercised (in dollars per share) | $ / shares	17.05
Weighted average exercise price - options forfeited (in dollars per share) | $ / shares	27.67
Weighted average exercise price - options expired (in dollars per share) | $ / shares	24.66
Weighted average exercise price ending balance (in dollars per share) | $ / shares	$ 28.42
Number of RSU Shares
RSUs granted (in shares)	797,290
RSUs forfeited (in shares)	(226,564)
Restricted Stock Units
Shares Available for Grant
RSUs granted (in shares)	(797,290)
RSUs forfeited (in shares)	226,564
Number of RSU Shares
Number of RSU shares beginning balance (in shares)	1,878,866
RSUs granted (in shares)	797,290
RSUs vested (in shares)	(639,335)
RSUs forfeited (in shares)	(226,564)
Number of RSU shares ending balance (in shares)	1,810,257
Weighted- Average Grant Date Fair Value
Weighted average grant date fair value beginning balance (in dollars per share) | $ / shares	$ 28.42
Weighted average grant date fair value - RSUs granted (in dollars per share) | $ / shares	79.36
Weighted average grant date fair value - RSUs vested (in dollars per share) | $ / shares	24.82
Weighted average grant date fair value - RSUs forfeited (in dollars per share) | $ / shares	40.29
Weighted average grant date fair value ending balance (in dollars per share) | $ / shares	$ 50.94