Equity - Summary of Stock Option Activity (Detail) - $ / shares	9 Months Ended
	Sep. 30, 2019
Number of shares
Beginning balance (in shares)	6,839,417
Options granted (in shares)	943,345
Less:
Options exercised (in shares)	1,439,869
Options canceled or expired (in shares)	174,927
Ending balance (in shares)	6,167,966
Exercisable at September 30, 2019 (in shares)	2,995,419
Weighted Average Exercise Price
Weighted average exercise price, beginning balance (in dollars per share)	$ 7.63
Weighted average exercise price, granted (in dollars per share)	19.74
Less:
Weighted average exercise price, exercised (in dollars per share)	6.58
Weighted average exercise price, canceled or expired (in dollars per share)	13.15
Weighted average exercise price, ending balance (in dollars per share)	9.56
Weighted average exercise price, exercisable, ending balance (in dollars per share)	$ 7.20