Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total		Common Stock		Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2018	[1]	$ 234,942		$ 4		$ 357,873	$ (122,828)	$ (107)
Balance, shares at Dec. 31, 2018	[1]			43,610,823
Cumulative effect adjustment upon adoption of ASC 606 | ASC 606		2,212					2,212
Issuance of common stock upon exercise of stock options, shares				69
Vesting of early exercised stock options and restricted stock		273				273
Vesting of early exercised stock options and restricted stock, shares				114,934
Stock-based compensation		1,674				1,674
Other comprehensive loss		136						136
Net loss		(17,670)					(17,670)
Balance at Mar. 31, 2019		221,567		$ 4		359,820	(138,286)	29
Balance, shares at Mar. 31, 2019				43,725,826
Balance at Dec. 31, 2019	[1]	$ 163,842	[2]	$ 4		369,100	(205,326)	64
Balance, shares at Dec. 31, 2019		45,925,004		44,212,195	[1]
Issuance of common stock upon exercise of stock options		$ 643				643
Issuance of common stock upon exercise of stock options, shares				59,939
Vesting of early exercised stock options and restricted stock		220				220
Vesting of early exercised stock options and restricted stock, shares				77,388
Stock-based compensation		3,462				3,462
Other comprehensive loss		224						224
Net loss		(27,753)					(27,753)
Balance at Mar. 31, 2020		$ 140,638		$ 4		$ 373,425	$ (233,079)	$ 288
Balance, shares at Mar. 31, 2020		45,982,788		44,349,522

[1] The balances as of December 31, 2019 and 2018 have been derived from the audited financial statements as of that date.

[2] The Condensed Consolidated Balance Sheet as of December 31, 2019 has been derived from the audited financial statements as of that date.