Stock-Based Compensation - Additional Information (Details)	1 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021 USD ($) offeringPeriod hour plan $ / shares shares	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of plans | plan		3
Vesting period (in years)		4 years
Weighted average period for recognition of compensation costs (in years)		1 year 2 months 12 days
Expiration period of stock option plan (in years)		10 years
Options granted (in shares) | shares		0
Weighted average grant date fair value of options granted, per share (in dollars per share) | $ / shares			$ 1.20	$ 4.67
Aggregate intrinsic value of options exercised				$ 7,800,000
Unrecognized compensation cost		$ 4,300,000
Stock-based compensation expense		$ 23,871,000	$ 22,805,000	$ 19,445,000
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value of RSUs granted (in dollars per share) | $ / shares		$ 4.87	$ 2.80	$ 3.63
Total grant date fair value of RSUs		$ 16,800,000	$ 17,000,000	$ 12,200,000
Total fair value of RSUs vested		27,500,000	5,100,000	6,400,000
Unrecognized stock based compensation cost		$ 14,900,000
Weighted average period for recognition of compensation costs (in years)		1 year 8 months 12 days
Shares expected to vest (in shares) | shares		6,000,000
Restricted Stock Units (RSUs) | Employees | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (in years)		3 years
Restricted Stock Units (RSUs) | Employees | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (in years)		1 year
Employee Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Minimum hours worked per week | hour		20
Minimum months worked (in months)		5 months
2015 and 2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for grant (in shares) | shares		5,800,000
2015 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum contribution percentage amount of employee's base compensation (as a percent)		15.00%
Maximum employee contribution in to share purchase plan per offering		$ 30,000
Number of common stock authorized for issuance (in shares) | shares		3,000
Percentage of market value price of common stock under Employee Stock Purchase Plan (as a percent)		85.00%
Common stock reserved for issuance (in shares) | shares		3,500,000
Shares issued under ESPP (in shares) | shares		300,000
Common stock remained available for issuance pursuant to the purchase plan (in shares) | shares		3,200,000
Number of offering periods | offeringPeriod		2
Stock-based compensation expense		$ 300,000	$ 100,000	$ 0
2015 Employee Stock Purchase Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock authorized for issuance (in shares) | shares		3,500,000
2015 Employee Stock Purchase Plan | Employee Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock based compensation cost		$ 0
Two Thousand and Twenty One Performance Share Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance period (in years)	3 years