Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Deferred tax assets (DTAs):
Net operating loss and tax credit carryforwards	$ 37,872	$ 35,796
Unrealized mark-to-market, impairments and loss provisions	465	3,753
Other realized / unrealized treatment differences	12,893	12,131
Total deferred tax assets	51,230	51,680
Less: valuation allowance	(51,230)	(51,680)
Net deferred tax assets	$ 0	$ 0