Related Party Transactions - Additional Information (Details) - USD ($)		3 Months Ended		9 Months Ended
	Apr. 15, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	May 31, 2017
Related Party Transaction [Line Items]
Proceeds from note payable due to related party				$ 12,400,000	$ 4,225,000
PDL BioPharma, Inc
Related Party Transaction [Line Items]
Expenses from transactions with related party		$ 637,000	$ 917,000	3,387,000	3,178,000
Expense related to allocation of corporate costs		1,098,000		1,098,000		$ 142,000
Costs associated with spin-off transaction		0		0
Maximum aggregate principal amount	$ 32,600,000						$ 25,600,000
Line of credit limit increased amount	$ 7,000,000
Proceeds from note payable due to related party				12,400,000
Interest expense		$ 33,000	$ 112,000	$ 511,000	$ 302,000