Net Assets in Liquidation (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 01, 2020	Dec. 31, 2020	Dec. 31, 2018	Aug. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Liquidation Basis Of Accounting [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ 729,779	$ 425,214	$ 593,278	$ 845,890
Effect of adopting the liquidation basis of accounting	$ (21,339)
Liquidation Basis of Accounting, Net Assets (Liabilities)	446,553	$ 386,919		446,553
Assets [Member]
Liquidation Basis Of Accounting [Line Items]
Quantifying Misstatement in Current Year Financial Statements, Amount		$ 3,000	$ 9,800
Royalty Assets
Liquidation Basis Of Accounting [Line Items]
Royalty assets	231,683			217,913
Change in royalty assets	13,770
Assertio
Liquidation Basis Of Accounting [Line Items]
Royalty assets	211,626			200,463
Change in royalty assets	11,163
U-M
Liquidation Basis Of Accounting [Line Items]
Royalty assets	20,057			$ 17,450
Change in royalty assets	2,607
Change in the estimated value of royalty rights
Liquidation Basis Of Accounting [Line Items]
Effect of adopting the liquidation basis of accounting	(13,770)
Change in the receivable from the sale of Noden
Liquidation Basis Of Accounting [Line Items]
Effect of adopting the liquidation basis of accounting	(9,056)
Estimated value of LENSAR
Liquidation Basis Of Accounting [Line Items]
Effect of adopting the liquidation basis of accounting	(28,702)
Change in the estimated value of other assets
Liquidation Basis Of Accounting [Line Items]
Effect of adopting the liquidation basis of accounting	(4,813)
Estimated liquidation and future operating costs
Liquidation Basis Of Accounting [Line Items]
Effect of adopting the liquidation basis of accounting	$ (25,376)