Gas Reserves - Investment - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Reserve Quantities [Line Items]
Gas reserves	$ 12,265	$ 15,278	$ 16,392
Gas reserves, non-current	175,042	172,029	170,915
Less: Accumulated amortization	137,346	123,635	118,937
Total gas reserves	49,961	63,672	68,370
Less: Deferred taxes on gas reserves	11,972	15,515	13,293
Net investment in gas reserves	37,989	48,157	55,077
Jonah Energy LLC
Reserve Quantities [Line Items]
Total Gas Reserves Investment	$ 3,200	$ 3,800	$ 4,000