Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred noncurrent income tax assets (liabilities):
Oil & gas properties	$ 20,909	$ 18,929
Basis difference in subsidiary obligation	(2,211)	(2,211)
Investment in Partnerships	(27,463)	(25,760)
Federal net operating loss carryforward	16,544	11,590
Net deferred noncurrent tax (liability) asset	7,779	2,548
Valuation allowance	(23,510)	(17,044)
Net deferred tax liability	$ (15,731)	$ (14,496)