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Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue from Contracts with Customers
Revenue	$ 59,874	$ 72,318	$ 145,880	$ 150,016
Receivables, net	48,141		48,141		$ 61,760
Contract Assets - Current	1,537		1,537		455
Contract Assets - Noncurrent	3,829		3,829		3,777
Contract Assets - Total	5,366		5,366		4,232
Contract Liabilities - Current	2,044		2,044		5,329
Contract Liabilities - Noncurrent					6,339
Contract Liabilities - Total	2,044		2,044		$ 11,668
Volume -Related
Revenue from Contracts with Customers
Revenue	50,231	66,260	125,290	140,788
Volume -Related \| Commodity swaps
Revenue from Contracts with Customers
Gain on derivatives		600
Loss on derivatives	1,500			4,400
Volume -Related \| Fueling agreements
Revenue from Contracts with Customers
Gain on derivatives			4,200
Station construction sales
Revenue from Contracts with Customers
Revenue	5,277	5,943	10,800	9,113
AFTC
Revenue from Contracts with Customers
Revenue	$ 4,366		$ 9,790
Other
Revenue from Contracts with Customers
Revenue		$ 115		$ 115