Income Taxes - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets:
Investments in subsidiaries	$ 13,686	$ 7,099
Imputed interest	1,594	1,587
Net operating loss carryforward	45,339	43,543
Total deferred tax assets	60,619	52,229
Net deferred tax asset	$ 60,619	$ 52,229