Revenue from Contracts with Customers (Contract with Customer, Asset and Liability) (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Contract liability		$ 8,513	$ 9,881
Mid-Stream [Member]
Disaggregation of Revenue [Line Items]
Contract assets	[1]	13,078	13,164
Amounts invoiced in excess of revenue recognized		(86)
Contract with Customer, Asset, Net, Current		3,400	300
Contract with Customer, Asset, Net, Noncurrent		9,700	12,900
Contract liability	[2]	8,513	9,882
New contract		60
Contract with Customer, Liability, Revenue Recognized		(1,429)
Contract with Customer, Liability, Current		2,900	2,900
Contract with Customer, Liability, Noncurrent		$ 5,600	$ 7,000

[1] At December 31, 2018, total contract assets are included in prepaid expenses and other and other assets of $0.3 million and $12.9 million, respectively, in our Consolidated Balance Sheet. At June 30, 2019, total contract assets included prepaid expenses and other and other assets of $3.4 million and $9.7 million, respectively, in our Condensed Consolidated Balance Sheet.

[2] At December 31, 2018, total contract liabilities are included in current portion of other long-term liabilities and other long-term liabilities of $2.9 million and $7.0 million, respectively, in our Consolidated Balance Sheet. At June 30, 2019, total contract liabilities included current portion of other long-term liabilities and other long-term liabilities of $2.9 million and $5.6 million, respectively, in our Condensed Consolidated Balance Sheet.