Long-Term Debt And Other Long-Term Liabilities (Narrative) (Details) - USD ($) $ in Thousands			6 Months Ended
	May 02, 2018	Apr. 03, 2018	Jun. 30, 2018	Apr. 02, 2018	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, 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			$ 14,000
Estimated principal payments in year 2			43,800
Estimated principal payments in year 3			660,600
Estimated principal payments in year 4			5,000
Estimated principal payments in year 5			$ 2,700
Number of compressors under capital lease agreement			20
Capital lease term			7 years
Capital Lease Obligations, Current			$ 3,900
Capital Lease Obligations, Noncurrent			$ 9,400
Discount rate capital leases			4.00%
Maintenance			$ 4,981
Interest			886
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					$ 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) in excess of $200.0 million
Current ratio of credit facility			1 to 1
Unit Credit Agreement, Covenant Compliance			As of June 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					475,000
Unit Credit Agreement [Member] | Line Of Credit Facility Commitment Amount [Member]
Debt Instrument [Line Items]
Credit facility current credit amount					$ 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%
Unit Credit Agreement [Member] | Apr 8, 2016 to Mar 31, 2019 [Member]
Debt Instrument [Line Items]
Senior indebtedness ratio			2.75 to 1
Unit Credit Agreement [Member] | Apr 1, 2019 to Apr 10, 2020 [Member]
Debt Instrument [Line Items]
Leverage ratio of funded debt			4 to 1
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
Unit Credit Agreement, Covenant Compliance			As of June 30, 2018, we were 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]
Credit facility maximum credit amount				$ 425,000
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
Origination, agency and syndication and other related fees with the credit agreement				0
Fourth Amendment to Credit Agreement [Member] | Unit Credit Agreement [Member] | Line Of Credit Facility Lender Determined Amount [Member]
Debt Instrument [Line Items]
Credit facility current credit amount				425,000
Fourth Amendment to Credit Agreement [Member] | Unit Credit Agreement [Member] | Line Of Credit Facility Commitment Amount [Member]
Debt Instrument [Line Items]
Credit facility current credit amount				$ 425,000