Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Employee	Nonemployee	Common Stock	Additional paid-in Capital	Additional paid-in Capital Employee	Additional paid-in Capital Nonemployee	Accumulated Deficit
Balance at beginning of period (in shares) at Dec. 31, 2019				58,877,000
Balance at beginning of period at Dec. 31, 2019	$ 105,517			$ 6	$ 447,920			$ (342,409)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	87,240			87,000
Exercise of stock options	$ 539				539
Release of stock awards (in shares)				370,000
Taxes paid related to net shares settlement of equity awards (in shares)				(102,000)
Taxes paid related to net shares settlement of equity awards	(1,257)				(1,257)
Employee stock-based compensation		$ 6,045	$ 47			$ 6,045	$ 47
Net income (loss)	(20,090)							(20,090)
Balance at end of period (in shares) at Sep. 30, 2020				59,232,000
Balance at end of period at Sep. 30, 2020	90,801			$ 6	453,294			(362,499)
Balance at beginning of period (in shares) at Jun. 30, 2020				59,125,000
Balance at beginning of period at Jun. 30, 2020	94,786			$ 6	451,185			(356,405)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)				55,000
Exercise of stock options	342				342
Release of stock awards (in shares)				70,000
Taxes paid related to net shares settlement of equity awards (in shares)				(18,000)
Taxes paid related to net shares settlement of equity awards	(217)				(217)
Employee stock-based compensation		1,941	43			1,941	43
Net income (loss)	(6,094)							(6,094)
Balance at end of period (in shares) at Sep. 30, 2020				59,232,000
Balance at end of period at Sep. 30, 2020	90,801			$ 6	453,294			(362,499)
Balance at beginning of period (in shares) at Dec. 31, 2020				64,283,000
Balance at beginning of period at Dec. 31, 2020	$ 170,103			$ 6	536,516			(366,419)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	422,964			423,000
Exercise of stock options	$ 2,700				2,700
Release of stock awards (in shares)				181,000
Taxes paid related to net shares settlement of equity awards (in shares)				(54,000)
Taxes paid related to net shares settlement of equity awards	(1,206)				(1,206)
Employee stock-based compensation		8,360	187			8,360	187
Net income (loss)	(11,089)							(11,089)
Balance at end of period (in shares) at Sep. 30, 2021				64,833,000
Balance at end of period at Sep. 30, 2021	169,055			$ 6	546,557			(377,508)
Balance at beginning of period (in shares) at Jun. 30, 2021				64,623,000
Balance at beginning of period at Jun. 30, 2021	162,773			$ 6	542,519			(379,752)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)				210,000
Exercise of stock options	1,022				1,022
Employee stock-based compensation		$ 2,955	$ 61			$ 2,955	$ 61
Net income (loss)	2,244							2,244
Balance at end of period (in shares) at Sep. 30, 2021				64,833,000
Balance at end of period at Sep. 30, 2021	$ 169,055			$ 6	$ 546,557			$ (377,508)