Revenue from Contracts with Customers (Contract with Customer, Asset and Liability) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Contract liability	$ 2,077	$ 4,172
Mid-Stream [Member]
Disaggregation of Revenue [Line Items]
Current contract assets	1,700	6,084
Non-current contract assets	0	173
Contract assets	1,700	6,257
Contract with Customer, Current Asset, Reclassified to Receivable	(4,384)
Contract with Customer, Non-current Asset, Reclassified to Receivable	(173)
Change in contract assets	(4,557)
Current Contract Liabilities	1,919	2,583
Non-current contract liabilities	158	1,589
Contract liability	2,077	4,172
Contract with Customer, Current Liability, Revenue Recognized	(664)
Contract with Customer, Non-current Liability, Revenue Recognized	(1,431)
Change in contract assets (liabilities)	(2,095)
Contract asset (liabilities), net	(377)	$ 2,085
Change in contract liabilities	$ (2,462)