Long-Term Debt And Other Long-Term Liabilities (Narrative) (Details) - USD ($) $ in Thousands		12 Months Ended
	May 02, 2018	Dec. 31, 2018	Apr. 02, 2018	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Oil and Gas Property, Full Cost Method, Discount Percentage		10.00%
Variable Interest Entity, Date Involvement Began		Apr. 03, 2018
Aggregate principal amount		$ 650,000			$ 650,000
Interest percentage of senior subordinated notes		6.625%
Debt Instrument, Maturity Date		May 15, 2021
Deducting fees for debt issuance		$ 14,700
Senior notes repurchase price in percentage		101.00%
Senior Notes, Covenant Compliance		We were in compliance with all covenants of the Notes
Principal Payments Year One		$ 14,200
Principal Payments Year Two		9,400
Principal Payments Year Three		692,000
Principal Payments Year Four		3,900
Principal Payments Year Five		$ 2,200
Number of compressors under capital lease agreement		20
Capital lease term		7 years
Capital Lease Obligations, Current		$ 4,000
Capital Lease Obligations, Noncurrent		$ 7,400
Discount rate capital leases		4.00%
Maintenance		$ 4,089
Interest		635
Capital leases, future minimum payments, average annual payment		$ 4,300
Capital lease fair market value percentage for purchase		10.00%
Unit Credit Agreement [Member]
Debt Instrument [Line Items]
Credit facility maturity date		October 18, 2023
Commitment fee percentage under credit facility		0.375%
Origination, agency and syndication fees		$ 3,300
Credit Facility Maximum Credit Amount			$ 425,000	$ 875,000
Debt instrument, variable interest rate, payable assessment period		90 days
LIBOR interest rate plus one percent plus a margin		LIBOR plus 1.00% plus a margin
Line of credit facility, amount borrowed		$ 0			178,000
Unit Credit Agreement, Dividend Restrictions		the payment of dividends (other than stock dividends) during any fiscal year over 30% of our consolidated net income for the preceding fiscal year;
Unit Credit Agreement, Asset Restrictions		investments in Unrestricted Subsidiaries (as defined in the Unit credit agreement) over $200.0 million.
Current ratio of credit facility		1 to 1
Leverage ratio of long-term debt		4 to 1
Covenant Compliance		we were in compliance with the covenants contained in the Unit credit agreement.
Unit Credit Agreement [Member] | Minimum
Debt Instrument [Line Items]
LIBOR plus interest rate		1.50%
Unit Credit Agreement [Member] | Maximum
Debt Instrument [Line Items]
LIBOR plus interest rate		2.50%
Unit Credit Agreement [Member] | Line Of Credit Facility Commitment Amount
Debt Instrument [Line Items]
Credit facility current credit amount			425,000	475,000
Unit Credit Agreement [Member] | Line Of Credit Facility Lender Determined Amount
Debt Instrument [Line Items]
Credit facility current credit amount			$ 425,000	$ 475,000
Unit Credit Agreement [Member] | Proved developed producing total value of our oil and gas properties
Debt Instrument [Line Items]
Percentage of collateral pledged		80.00%
Oil and Gas Property, Full Cost Method, Discount Percentage		8.00%
Superior Credit Agreement [Member]
Debt Instrument [Line Items]
Commitment fee percentage under credit facility		0.375%
Origination, agency and syndication fees		$ 1,700
Credit Facility Maximum Credit Amount		250,000
Credit facility current credit amount		200,000
Line of credit facility, amount borrowed		$ 0			$ 0
Covenant Compliance		Superior was in compliance with the Superior credit agreement covenants
Superior Credit Agreement, Initiation Date		May 10, 2018
Superior Credit Agreement, Term		5 years
Superior Credit Agreement, Interest Rate Description		annual interest at a rate, at Superior’s option, equal to (a) LIBOR plus the applicable margin of 2.00% to 3.25% or (b) the alternate base rate (greater of (i) the federal funds rate plus 0.5%, (ii) the prime rate, and (iii) third day LIBOR plus 1.00%) plus the applicable margin of 1.00% to 2.25%.
Consolidated EBITDA to interest expense ratio		2.50 to 1.00
Funded debt to consolidated EBITDA ratio		4.00 to 1.00
Pledge Agreement | Unit Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Collateral	we granted a security interest in the limited liability membership interests and other equity interests we own in Superior (which as of the date of this report is 50% of the aggregate outstanding equity interests of Superior)