Long-Term Debt And Other Long-Term Liabilities (Narrative) (Details) - USD ($) $ in Thousands			9 Months Ended
	May 02, 2018	Apr. 03, 2018	Sep. 30, 2018	Apr. 02, 2018	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
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
Original debt issuance fees			$ 14,700
Senior notes repurchase price in percentage			101.00%
Estimated principal payments in year 1			$ 14,100
Estimated principal payments in year 2			43,100
Estimated principal payments in year 3			659,800
Estimated principal payments in year 4			4,600
Estimated principal payments in year 5			$ 2,300
Number of compressors under capital lease agreement			20
Capital lease term			7 years
Capital Lease Obligations, Current			$ 4,000
Capital Lease Obligations, Noncurrent			$ 8,400
Discount rate capital leases			4.00%
Maintenance			$ 4,601
Interest			756
Capital leases, future minimum payments, average annual payment			$ 4,200
Capital lease fair market value percentage for purchase			10.00%
6.625% Senior Subordinated Notes Due 2021 [Member]
Debt Instrument [Line Items]
Aggregate principal amount			$ 650,000
Unit Credit Agreement [Member]
Debt Instrument [Line Items]
Credit facility maturity date			April 10, 2020
Credit facility maximum credit amount				$ 425,000	$ 875,000
Commitment fee percentage under credit facility			0.50%
Origination, agency and syndication and other related fees with the credit agreement			$ 1,000
Payable assessment term for LIBOR			90 days
Line of credit facility, amount outstanding			$ 0			178,000
LIBOR interest rate plus one percent			LIBOR plus 1.00% plus a margin
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 funded debt			4 to 1
Covenant Compliance			As of September 30, 2018, we were in compliance with the Unit credit agreement covenants.
Unit Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate			2.00%
Unit Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
LIBOR plus interest rate			3.00%
Unit Credit Agreement [Member] | Line Of Credit Facility Lender Determined Amount [Member]
Debt Instrument [Line Items]
Credit facility current credit amount				425,000	475,000
Unit Credit Agreement [Member] | Line Of Credit Facility Commitment Amount [Member]
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 [Member]
Debt Instrument [Line Items]
Percentage of collateral pledged			85.00%
Present worth discounted			8.00%
Superior Credit Agreement [Member]
Debt Instrument [Line Items]
Credit facility maximum credit amount			$ 250,000
Credit facility current credit amount			$ 200,000
Commitment fee percentage under credit facility			0.375%
Origination, agency and syndication and other related fees with the credit agreement			$ 1,700
Line of credit facility, amount outstanding			$ 0			$ 0
Covenant Compliance			As of September 30, 2018, 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%.
Superior Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Consolidated EBITDA to interest expense ratio			2.50 to 1.00
Superior Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Funded debt to consolidated EBITDA ratio			4.00 to 1.00
Fourth Amendment to Credit Agreement [Member] | 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 this report is 50% of the aggregate outstanding equity interests of Superior
Origination, agency and syndication and other related fees with the credit agreement				$ 0