Stock-Based Compensation - Narrative (Detail)	12 Months Ended
	Dec. 31, 2021 USD ($) offeringPeriod purchase_period shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	May 31, 2021 shares	May 29, 2020 shares	May 28, 2020 shares	May 31, 2019 shares	May 31, 2018 shares	Dec. 31, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (shares)	27,017,000	21,943,000
Intrinsic value of options exercised | $	$ 400,000	$ 5,100,000	$ 22,400,000
Stock-based compensation capitalized | $	1,000,000
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation costs | $	$ 54,400,000
Recognition over weighted average periods	2 years 7 months 6 days
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved (shares)					875,000	375,000
Number of additional shares authorized for issuance (shares)					31,250
Common stock reserved for future issuance (shares)	6,914,000	3,899,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of RSUs that vested | $	$ 5,000,000	$ 5,700,000	$ 1,900,000
2010 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	10 years
Vesting term	4 years
2010 Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved (shares)							7,500,000
2010 Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved (shares)							11,500,000
2010 Plan | ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (shares)	6,528,510
Restated 2010 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved (shares)				16,000,000
2013 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved (shares)								637,500	337,500
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limit on purchases under the ESPP per calendar year | $	$ 25,000
Employee Stock Purchase Plan | ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of each offering period under the ESPP	12 months
Number of purchase periods permitted under the ESPP | purchase_period	2
Duration of each purchase period under the ESPP	6 months
Number of offering periods permitted under the ESPP | offeringPeriod	2
Percentage of purchase price (percent)	85.00%
Maximum percentage of employee withholding (percent)	20.00%
Maximum number of shares per employee (shares)	5,000
Number of shares purchased during period (shares)	112,337	51,745	28,146
2021 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (shares)				1,000,000
2021 Inducement Plan | ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (shares)	385,515