CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Balances at beginning of period at Dec. 31, 2019	$ 21,060		$ 7	$ 299,263	$ (277,112)	$ (1,098)
Balances at beginning of period (in shares) at Dec. 31, 2019			6,810
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from vesting of restricted stock units	0		$ 0	0	0	0
Issuance of common stock from vesting of restricted stock units (in shares)			138
Tax withholding related to vesting of restricted stock units	(151)		$ 0	(151)	0	0
Issuance of common stock under employee stock purchase plan	14		$ 0	14	0	0
Issuance of common stock under employee stock purchase plan (in shares)			11
Stock-based compensation expense	1,013		$ 0	1,013	0	0
Net loss	(7,452)		0	0	(7,452)	0
Foreign currency translation adjustments	88		0	0	0	88
Balances at end of period at Jun. 30, 2020	14,572		$ 7	300,139	(284,564)	(1,010)
Balances at end of period (in shares) at Jun. 30, 2020			6,959
Balances at beginning of period at Dec. 31, 2019	21,060		$ 7	299,263	(277,112)	(1,098)
Balances at beginning of period (in shares) at Dec. 31, 2019			6,810
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(14,051)
Balances at end of period at Dec. 31, 2020	15,815	[1]	$ 10	308,065	(291,163)	(1,097)
Balances at end of period (in shares) at Dec. 31, 2020			9,743
Balances at beginning of period at Mar. 31, 2020	17,598		$ 7	299,689	(281,083)	(1,015)
Balances at beginning of period (in shares) at Mar. 31, 2020			6,830
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from vesting of restricted stock units	0		$ 0	0	0	0
Issuance of common stock from vesting of restricted stock units (in shares)			118
Tax withholding related to vesting of restricted stock units	(131)		$ 0	(131)	0	0
Issuance of common stock under employee stock purchase plan	14		$ 0	14	0	0
Issuance of common stock under employee stock purchase plan (in shares)			11
Stock-based compensation expense	567		$ 0	567	0	0
Net loss	(3,481)		0	0	(3,481)	0
Foreign currency translation adjustments	5		0	0	0	5
Balances at end of period at Jun. 30, 2020	14,572		$ 7	300,139	(284,564)	(1,010)
Balances at end of period (in shares) at Jun. 30, 2020			6,959
Balances at beginning of period at Dec. 31, 2020	15,815	[1]	$ 10	308,065	(291,163)	(1,097)
Balances at beginning of period (in shares) at Dec. 31, 2020			9,743
Balances at end of period at Mar. 31, 2021	16,830		$ 11	311,342	(293,375)	(1,148)
Balances at end of period (in shares) at Mar. 31, 2021			10,941
Balances at beginning of period at Dec. 31, 2020	15,815	[1]	$ 10	308,065	(291,163)	(1,097)
Balances at beginning of period (in shares) at Dec. 31, 2020			9,743
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock through equity distribution agreement, net of offering costs	3,025		$ 1	3,024	0	0
Issuance of common stock through equity distribution agreement, net of offering costs (in shares)			1,186
Issuance of common stock from vesting of restricted stock units	0		$ 0	0	0	0
Issuance of common stock from vesting of restricted stock units (in shares)			205
Tax withholding related to vesting of restricted stock units	(111)		$ 0	(111)	0	0
Issuance of common stock under employee stock purchase plan	16		$ 0	16	0	0
Issuance of common stock under employee stock purchase plan (in shares)			13
Stock-based compensation expense	681		$ 0	681	0	0
Net loss	(4,713)		0	0	(4,713)	0
Foreign currency translation adjustments	(36)		0	0	0	(36)
Balances at end of period at Jun. 30, 2021	14,677		$ 11	311,675	(295,876)	(1,133)
Balances at end of period (in shares) at Jun. 30, 2021			11,147
Balances at beginning of period at Mar. 31, 2021	16,830		$ 11	311,342	(293,375)	(1,148)
Balances at beginning of period (in shares) at Mar. 31, 2021			10,941
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from vesting of restricted stock units	0		$ 0	0	0	0
Issuance of common stock from vesting of restricted stock units (in shares)			193
Tax withholding related to vesting of restricted stock units	(88)		$ 0	(88)	0	0
Issuance of common stock under employee stock purchase plan	16		$ 0	16	0	0
Issuance of common stock under employee stock purchase plan (in shares)			13
Stock-based compensation expense	405		$ 0	405	0	0
Net loss	(2,501)		0	0	(2,501)	0
Foreign currency translation adjustments	15		0	0	0	15
Balances at end of period at Jun. 30, 2021	$ 14,677		$ 11	$ 311,675	$ (295,876)	$ (1,133)
Balances at end of period (in shares) at Jun. 30, 2021			11,147

[1] Derived from the Company’s audited consolidated financial statements as of December 31, 2020.