CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance at Dec. 31, 2019	$ (30,553)	$ (34)	$ 11	$ 7,621	$ (38,185)	$ (34)
Beginning Balance, Shares at Dec. 31, 2019			1,070
Accounting Standards Update [Extensible List]	ASC 326
Contributions from PDL	$ 1,519			1,519
Distributions to PDL	(97)			(97)
Settlement of phantom stock-based awards	783			783
Net loss	(3,686)				(3,686)
Ending Balance at Mar. 31, 2020	(32,068)		$ 11	9,826	(41,905)
Ending Balance, Shares at Mar. 31, 2020			1,070
Contributions from PDL	290			290
Net loss	(4,497)				(4,497)
Ending Balance at Jun. 30, 2020	(36,275)		$ 11	10,116	(46,402)
Ending Balance, Shares at Jun. 30, 2020			1,070
Impact from recapitalization transactions	69,879		$ 62	69,817
Impact from recapitalization transactions, Shares			6,221
Sale of common stock to PDL	16,431		$ 15	16,416
Sale of common stock to PDL, Shares			1,496
Capital contribution from PDL	20,666			20,666
Issuance of common stock			$ 18	(18)
Issuance of common stock, Shares			1,847
Stock-based compensation	3,857			3,857
Contributions from PDL	609			609
Distributions to PDL	(1,764)			(1,764)
Modification of phantom stock-based awards	306			306
Net loss	(4,763)				(4,763)
Ending Balance at Sep. 30, 2020	68,946		$ 106	120,005	(51,165)
Ending Balance, Shares at Sep. 30, 2020			10,634
Beginning Balance at Dec. 31, 2020	67,210		$ 109	125,094	(57,993)
Beginning Balance, Shares at Dec. 31, 2020			10,933
Stock-based compensation	2,301			2,301
Net loss	(5,182)				(5,182)
Ending Balance at Mar. 31, 2021	64,329		$ 109	127,395	(63,175)
Ending Balance, Shares at Mar. 31, 2021			10,933
Beginning Balance at Dec. 31, 2020	$ 67,210		$ 109	125,094	(57,993)
Beginning Balance, Shares at Dec. 31, 2020			10,933
Accounting Standards Update [Extensible List]	ASU 2019-12
Ending Balance at Sep. 30, 2021	$ 57,046		$ 110	130,628	(73,692)
Ending Balance, Shares at Sep. 30, 2021			10,957
Beginning Balance at Mar. 31, 2021	64,329		$ 109	127,395	(63,175)
Beginning Balance, Shares at Mar. 31, 2021			10,933
Issuance of common stock under the 2020 ESPP	170		$ 1	169
Issuance of common stock under the 2020 ESPP, Shares			24
Stock-based compensation	1,491			1,491
Net loss	(4,362)				(4,362)
Ending Balance at Jun. 30, 2021	61,628		$ 110	129,055	(67,537)
Ending Balance, Shares at Jun. 30, 2021			10,957
Stock-based compensation	1,573			1,573
Net loss	(6,155)				(6,155)
Ending Balance at Sep. 30, 2021	$ 57,046		$ 110	$ 130,628	$ (73,692)
Ending Balance, Shares at Sep. 30, 2021			10,957