Commitments And Contingencies (Lease Cost on Consolidated Statement of Operations) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Total lease costs	$ 5,192
Production Expense [Member]
Total lease costs	1,597
General and Administrative Expense [Member]
Total lease costs	49
Lease Costs Billed To Joint Venture Owners [Member]
Total lease costs	$ 3,546