Commitments and Contingencies (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other Commitments [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 2,700,000
Operating Leases, Future Minimum Payments, Due in Two Years	900,000
Operating Leases, Future Minimum Payments, Due in Three Years	400,000
Operating Leases, Future Minimum Payments, Due in Four Years	100,000
Operating Leases, Rent Expense, Net	$ 2,300,000	$ 2,100,000
Number of compressors under capital lease agreement	20
Capital lease term	7 years
Capital Leases, Future Minimum Payments Due, Next Twelve Months	$ 6,168,000
Capital Leases, Future Minimum Payments Due in Two Years	6,168,000
Capital Leases, Future Minimum Payments Due in Three Years	7,815,000
Capital Leases, Future Minimum Payments Due in Four Years	579,000
Maintenance	5,428,000
Interest	1,025,000
Capital leases, future minimum payments, average annual payment	$ 4,200,000
Capital lease fair market value percentage for purchase	10.00%
Percentage of repurchase of limited units outstanding	20.00%
Repurchase Of Limited Units Outstanding Amount	$ 0	$ 0
Drilling Equipment [Member]
Other Commitments [Line Items]
Other Commitment, Due in Next Twelve Months	$ 3,429,000