Revenue from Contracts with Customers (Contract with Customer, Asset and Liability) (Details) - USD ($) $ in Thousands	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2020	Aug. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Adoption of ASC606 [Line Items]
Current contract assets	$ 6,084		$ 6,084	$ 6,664
Non-current contract assets	173		173	6,257
Current contract liabilities	2,583		2,583	2,889
Change in current contract liabilities			(306)
Non-current contract liabilities	1,589		1,589	4,172
Change in noncurrent contract liabilities			(2,583)
Contract liability	4,172		4,172	7,061
Change in contact assets and liabilities, net	1,316	$ 2,459		(2,577)
Mid-Stream
Adoption of ASC606 [Line Items]
Change in current contract assets			(580)
Change in noncurrent contract assets			(6,084)
Total contract assets	6,257		6,257	12,921
Change in contract assets			(6,664)
Contract liability	4,172		4,172	7,061
Change in contract liabilities			(2,889)
Contract assets (liabilities), net	$ 2,085		2,085	5,860
Change in contact assets and liabilities, net			$ 3,775	$ (2,600)