Revenue Recognition (Narrative) (Details)	1 Months Ended
	Dec. 31, 2018 USD ($)
Revenue from Contract with Customer [Line Items]
Contract asset associated with revenues from contracts with customers	$ 0
Contract liability associated with revenues from contracts with customers	0
Gas Gathering [Member]
Revenue from Contract with Customer [Line Items]
Contract asset associated with revenues from contracts with customers	0
Contract liability associated with revenues from contracts with customers	$ 0
Fayetteville Shale [Member]
Revenue from Contract with Customer [Line Items]
Percentage of assets sold	100.00%