Quarterly Financial Information (Unaudited) - Statements of Changes in Stockholders' Equity (Details)			1 Months Ended			3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Jul. 06, 2022 shares	Apr. 04, 2022 shares	Jul. 31, 2022 USD ($) shares	Oct. 31, 2021 shares	Mar. 31, 2021 shares	Sep. 30, 2022 USD ($) shares	Jun. 30, 2022 USD ($) shares	Mar. 31, 2022 USD ($) shares	Jun. 30, 2022 USD ($) shares	Sep. 30, 2022 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares
Increase (decrease) in stockholders' equity
Balance			$ 2,369,000			$ 2,369,000	$ (5,358,000)	$ 3,915,000	$ 3,915,000	$ 3,915,000	$ 3,915,000	$ 49,328,000	$ 45,745,000
Share-based compensation - stock options and RSUs							669,000	764,000			2,492,000	3,338,000	2,818,000
Issuance of common stock upon exercise of options												75,000	610,000
Unrealized net gain on marketable securities												(3,000)	3,000
Net loss						(5,930,000)	(5,168,000)	(10,385,000)	(15,553,000)	(21,481,000)	(25,412,000)	(71,067,000)	(51,853,000)
Balance						(3,025,000)	$ 2,369,000	$ (5,358,000)	$ 2,369,000	$ (3,025,000)	$ (5,545,000)	$ 3,915,000	$ 49,328,000
Reverse stock split conversion ratio											0.025	0.025
Preferred Stock
Increase (decrease) in stockholders' equity
Balance (in shares) | shares							2,425
Balance (in shares) | shares								2,425
Common stock
Increase (decrease) in stockholders' equity
Balance			$ 1,000			$ 1,000
Balance (in shares) | shares			12,360,157			12,360,157	3,365,422	3,034,901	3,034,901	3,034,901	3,034,901	2,189,100	1,745,264
Fractional shares retired as a result of reverse split | shares							(10)				(11)
Issuance of common stock upon exercise of options (in shares) | shares												3,160	12,586
Conversion of convertible preferred stock (in shares) | shares		303,125
Vesting of RSUs (in shares) | shares							4,118	1,773			6,555	3,096
Balance						$ 4,000	$ 1,000		$ 1,000	$ 4,000	$ 4,000
Balance (in shares) | shares						39,026,823	12,360,157	3,365,422	12,360,157	39,026,823	42,970,134	3,034,901	2,189,100
Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Balance			$ 401,211,000			$ 401,211,000	$ 388,317,000	$ 387,205,000	$ 387,205,000	$ 387,205,000	$ 387,205,000	$ 361,548,000	$ 306,115,000
Share-based compensation - stock options and RSUs						536,000	669,000	764,000			2,492,000	3,338,000	2,818,000
Issuance of common stock upon exercise of options												75,000	610,000
Balance						401,744,000	401,211,000	388,317,000	401,211,000	401,744,000	403,153,000	387,205,000	361,548,000
Accumulated Other Comprehensive Income
Increase (decrease) in stockholders' equity
Balance												3,000
Unrealized net gain on marketable securities												(3,000)	3,000
Balance													3,000
Accumulated Deficit
Increase (decrease) in stockholders' equity
Balance			$ (398,843,000)			(398,843,000)	(393,675,000)	(383,290,000)	(383,290,000)	(383,290,000)	(383,290,000)	(312,223,000)	(260,370,000)
Net loss							(5,168,000)	(10,385,000)			(25,412,000)	(71,067,000)	(51,853,000)
Balance							(398,843,000)	$ (393,675,000)	(398,843,000)		$ (408,702,000)	(383,290,000)	(312,223,000)
Series A Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock (in shares) | shares								(2,425)			(2,425)
Series A Convertible Preferred Stock | Common stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock (in shares) | shares								303,125			303,125
Series B Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock							$ (2,425)
Conversion of convertible preferred stock (in shares) | shares											(2,425)
Series B Convertible Preferred Stock | Common stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock (in shares) | shares							303,125				303,125
Series A and B Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock (in shares) | shares								4,850			4,850
Public offering
Increase (decrease) in stockholders' equity
Issuance of common stock											$ 3,000	$ 11,898,000	$ 48,435,000
Issuance of common stock (in shares) | shares	7,518,334		7,518,334
Public offering | Common stock
Increase (decrease) in stockholders' equity
Issuance of common stock											$ 3,000
Issuance of common stock (in shares) | shares	19,148,332		19,148,332	666,666							26,666,666	666,666	431,250
Public offering | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Issuance of common stock												$ 11,898,000	$ 48,435,000
At-the-market sales
Increase (decrease) in stockholders' equity
Issuance of common stock							$ 12,226,000	$ 348,000			$ 13,457,000	$ 9,266,000
At-the-market sales | Common stock
Increase (decrease) in stockholders' equity
Issuance of common stock						$ 3,000	$ 1,000				$ 1,000
Issuance of common stock (in shares) | shares					172,879	26,666,666	8,687,502	25,623			12,655,773	172,879
At-the-market sales | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Issuance of common stock						$ (3,000)	$ 12,225,000	$ 348,000			$ 13,456,000	$ 9,266,000
Error Correction, Accounting for Warrants | As Previously Reported
Increase (decrease) in stockholders' equity
Balance			$ 3,419,000			3,419,000	2,743,000	9,271,000	9,271,000	9,271,000	$ 9,271,000	49,328,000
Share-based compensation - stock options and RSUs							669,000	764,000				3,338,000
Issuance of common stock							12,226,000
Issuance of common stock upon exercise of options												75,000
Registered direct financing costs, inclusive of warrants								(721,000)
Unrealized net gain on marketable securities												(3,000)
Net loss						(19,666,000)	(12,219,000)	(11,769,000)	(23,988,000)	(43,652,000)		(74,894,000)
Balance						6,260,000	3,419,000	2,743,000	$ 3,419,000	$ 6,260,000		$ 9,271,000	$ 49,328,000
Error Correction, Accounting for Warrants | As Previously Reported | Preferred Stock
Increase (decrease) in stockholders' equity
Balance							$ 887,000
Balance (in shares) | shares							2,425
Registered direct financing costs, inclusive of warrants								(965,000)
Warrants issued in connection with registered direct offering								(2,101,000)
Balance								$ 887,000
Balance (in shares) | shares								2,425
Error Correction, Accounting for Warrants | As Previously Reported | Common stock
Increase (decrease) in stockholders' equity
Balance			$ 1,000			$ 1,000
Balance (in shares) | shares			12,360,157			12,360,157	3,365,422	3,034,901	3,034,901	3,034,901	3,034,901	2,189,100
Fractional shares retired as a result of reverse split | shares							(10)
Issuance of common stock							$ 1,000
Issuance of common stock (in shares) | shares							8,687,502
Issuance of common stock upon exercise of options (in shares) | shares												3,160
Vesting of RSUs (in shares) | shares							4,118	1,773				3,096
Balance						$ 4,000	$ 1,000		$ 1,000	$ 4,000
Balance (in shares) | shares						39,026,823	12,360,157	3,365,422	12,360,157	39,026,823		3,034,901	2,189,100
Error Correction, Accounting for Warrants | As Previously Reported | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Balance			$ 414,523,000			$ 414,523,000	$ 400,742,000	$ 396,388,000	$ 396,388,000	$ 396,388,000	$ 396,388,000	$ 361,548,000
Share-based compensation - stock options and RSUs						536,000	669,000	764,000				3,338,000
Issuance of common stock							12,225,000
Issuance of common stock upon exercise of options												75,000
Registered direct financing costs, inclusive of warrants								244,000
Warrants issued in connection with registered direct offering								2,101,000
Balance						437,027,000	414,523,000	400,742,000	414,523,000	437,027,000		396,388,000	$ 361,548,000
Error Correction, Accounting for Warrants | As Previously Reported | Accumulated Other Comprehensive Income
Increase (decrease) in stockholders' equity
Balance												3,000
Unrealized net gain on marketable securities												(3,000)
Balance													3,000
Error Correction, Accounting for Warrants | As Previously Reported | Accumulated Deficit
Increase (decrease) in stockholders' equity
Balance			(411,105,000)			(411,105,000)	(398,886,000)	(387,117,000)	(387,117,000)	(387,117,000)	(387,117,000)	(312,223,000)
Net loss							(12,219,000)	(11,769,000)				(74,894,000)
Balance							(411,105,000)	(398,886,000)	(411,105,000)			(387,117,000)	$ (312,223,000)
Error Correction, Accounting for Warrants | As Previously Reported | Series A Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								$ (897,000)
Conversion of convertible preferred stock (in shares) | shares								(2,425)
Error Correction, Accounting for Warrants | As Previously Reported | Series A Convertible Preferred Stock | Common stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock (in shares) | shares								303,125
Error Correction, Accounting for Warrants | As Previously Reported | Series A Convertible Preferred Stock | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								$ 897,000
Error Correction, Accounting for Warrants | As Previously Reported | Series B Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock							$ (887,000)
Conversion of convertible preferred stock (in shares) | shares							(2,425)
Error Correction, Accounting for Warrants | As Previously Reported | Series B Convertible Preferred Stock | Common stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock (in shares) | shares							303,125
Error Correction, Accounting for Warrants | As Previously Reported | Series B Convertible Preferred Stock | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock							$ 887,000
Error Correction, Accounting for Warrants | As Previously Reported | Series A and B Convertible Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								4,850,000
Error Correction, Accounting for Warrants | As Previously Reported | Series A and B Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								$ 4,850,000
Conversion of convertible preferred stock (in shares) | shares								4,850
Error Correction, Accounting for Warrants | As Previously Reported | Public offering
Increase (decrease) in stockholders' equity
Issuance of common stock												$ 21,081,000
Error Correction, Accounting for Warrants | As Previously Reported | Public offering | Common stock
Increase (decrease) in stockholders' equity
Issuance of common stock (in shares) | shares												666,666
Error Correction, Accounting for Warrants | As Previously Reported | Public offering | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Issuance of common stock												$ 21,081,000
Error Correction, Accounting for Warrants | As Previously Reported | At-the-market sales
Increase (decrease) in stockholders' equity
Issuance of common stock								$ 348,000				$ 9,266,000
Error Correction, Accounting for Warrants | As Previously Reported | At-the-market sales | Common stock
Increase (decrease) in stockholders' equity
Issuance of common stock						$ 3,000
Issuance of common stock (in shares) | shares						26,666,666		25,623				172,879
Error Correction, Accounting for Warrants | As Previously Reported | At-the-market sales | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Issuance of common stock						$ 21,968,000		$ 348,000				$ 9,266,000
Error Correction, Accounting for Warrants | Error Correction, Adjustment
Increase (decrease) in stockholders' equity
Balance			(1,050,000)			(1,050,000)	(8,101,000)	$ (5,356,000)	$ (5,356,000)	$ (5,356,000)	$ (5,356,000)
Balance (in shares) | shares								(5,356,000)	(5,356,000)	(5,356,000)	(5,356,000)
Registered direct financing costs, inclusive of warrants								$ 721,000
Net loss						13,736,000	7,051,000	1,384,000	$ 8,435,000	$ 22,171,000		3,827,000
Balance						(9,285,000)	(1,050,000)	(8,101,000)	(1,050,000)	(9,285,000)		$ (5,356,000)
Balance (in shares) | shares												(5,356,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Preferred Stock
Increase (decrease) in stockholders' equity
Balance							(887,000)
Registered direct financing costs, inclusive of warrants								965,000
Warrants issued in connection with registered direct offering								2,101,000
Balance								(887,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Balance			(13,312,000)			(13,312,000)	(12,425,000)	$ (9,183,000)	$ (9,183,000)	$ (9,183,000)	$ (9,183,000)
Balance (in shares) | shares								(9,183,000)	(9,183,000)	(9,183,000)	(9,183,000)
Registered direct financing costs, inclusive of warrants								$ (244,000)
Warrants issued in connection with registered direct offering								(2,101,000)
Balance						(35,283,000)	(13,312,000)	(12,425,000)	$ (13,312,000)	$ (35,283,000)		$ (9,183,000)
Balance (in shares) | shares												(9,183,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Accumulated Deficit
Increase (decrease) in stockholders' equity
Balance			$ 12,262,000			12,262,000	5,211,000	$ 3,827,000	$ 3,827,000	$ 3,827,000	$ 3,827,000
Balance (in shares) | shares								3,827,000	3,827,000	3,827,000	3,827,000
Net loss							7,051,000	$ 1,384,000				$ 3,827,000
Balance							12,262,000	5,211,000	$ 12,262,000			$ 3,827,000
Balance (in shares) | shares												3,827,000
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Series A Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								897,000
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Series A Convertible Preferred Stock | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								(897,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Series B Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock							887,000
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Series B Convertible Preferred Stock | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock							$ (887,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Series A and B Convertible Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								(4,850,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Series A and B Convertible Preferred Stock | Preferred Stock
Increase (decrease) in stockholders' equity
Conversion of convertible preferred stock								$ (4,850,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Public offering
Increase (decrease) in stockholders' equity
Issuance of common stock												$ (9,183,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | Public offering | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Issuance of common stock												$ (9,183,000)
Error Correction, Accounting for Warrants | Error Correction, Adjustment | At-the-market sales | Additional Paid in Capital.
Increase (decrease) in stockholders' equity
Issuance of common stock						$ (21,971,000)