Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	May 31, 2019	Nov. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option cancellation agreement, vested options to purchase (in shares)			700,000	0	1,256,200
Exercise price of stock options granted (in usd per share)			$ 33.98	$ 0	$ 11.92
Service period (in years)			5 years 9 months 18 days	6 years 4 months 24 days	6 years 7 months 6 days	6 years 6 months
Weighted average grant-date fair value of options granted (in usd per share)			$ 13.57		$ 5.05
Total fair value of stock options vested			$ 2,000,000.0	$ 10,500,000	$ 5,600,000
Total compensation cost related to unvested stock options not yet recognized			$ 8,400,000
Weighted average period, unvested stock options			1 year 10 months 24 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested restricted stock units			$ 28,800,000
Weighted average remaining vesting period			2 years 4 months 24 days
Granted (in shares)			436,912	622,166	738,055
Granted (in usd per share)			$ 40.70	$ 29.60	$ 22.15
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued (in shares)			4,668,941
2017 Equity Incentive Plan | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of awards at grant date		$ 7,700,000
Granted (in shares)		255,930
Granted (in usd per share)		$ 30.06
2017 Equity Incentive Plan | Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued (in shares)			7,108,049				6,421,442
2017 Equity Incentive Plan | Chief Financial Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option cancellation agreement, vested options to purchase (in shares)	700,000
Exercise price of stock options granted (in usd per share)	$ 33.98
Share price (in usd per share)	$ 84.63
Value of awards at grant date	$ 9,500,000
Service period (in years)	2 years 7 months 6 days
2007 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued (in shares)							421,442
Number of shares available for grants (in shares)							0