Stockholders' Equity (Deficit) and Stock-Based Compensation - Additional Information (Details)		1 Months Ended	3 Months Ended
	Feb. 15, 2018 USD ($) $ / shares shares	Jan. 31, 2018 shares	Mar. 31, 2018 USD ($) VotingRight shares	Mar. 31, 2017 USD ($)	Dec. 31, 2017 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, authorized			200,000,000		200,000,000
Common stock, Issued			34,287,944		30,860,241
Common stock, outstanding			34,287,944		30,860,241
Dividends paid or declared | $			$ 0
Common stock voting rights			Each share of common stock has the right to one vote on all matters submitted to a vote of stockholders.
Number of common stock voting rights | VotingRight			1
Proceeds from issuance of common stock from employee equity plans | $			$ 2,832,000	$ 1,038,000
Options outstanding			1,683,000		2,010,000
Unrecognized stock-based compensation costs related to non-vested awards | $			$ 5,523,000
Weighted-average period for unrecognized compensation cost expected to be recognized			2 years 7 months 6 days
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period for unrecognized compensation cost expected to be recognized			3 years 1 month 6 days
Unrecognized stock-based compensation costs | $			$ 50,055,000
2010 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grants			0
Options outstanding			1,250,318
2015 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grants			2,777,618
Increase in share reserve under the plan		1,388,709
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grants			661,223
Increase in share reserve under the plan		308,602
Initial offering expiration period			27 months
Percentage of discount through payroll deductions to eligible employees to purchase common stock			15.00%
Unrecognized stock-based compensation costs | $			$ 371,000
Weighted average date for unrecognized compensation cost to expected to be recognized			May 31, 2018
Morgan Stanley & Co. LLC and Credit Suisse Securities (USA) LLC | Underwriting Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares issuance and sale in public offering under the underwriting agreement	2,500,000
Common stock, par value | $ / shares	$ 0.0001
Price of common stock in public offering per share | $ / shares	39.50
Underwriting agreement of common stock price per share | $ / shares	$ 38.315
Common stock exercisable period for option to purchase of additional shares by underwriters	30 days
Common stock option to purchase additional shares by underwriters	375,000
Proceeds from issuance of common stock from employee equity plans | $	$ 109,800,000