Long-Term Debt And Other Long-Term Liabilities (Narrative) (Details) - USD ($) $ in Thousands		12 Months Ended
	May 02, 2018	Dec. 31, 2019	Jan. 17, 2020	Sep. 26, 2019	Dec. 31, 2018	Apr. 02, 2018
Debt Instrument [Line Items]
Oil and Gas Property, Full Cost Method, Discount Percentage		10.00%
Aggregate principal amount		$ 650,000			$ 650,000
Interest percentage of senior subordinated notes		6.625%
Debt Instrument, Maturity Date		May 15, 2021
Principal Payments Year One		$ 125,600
Principal Payments Year Two		659,300
Principal Payments Year Three		45,100
Principal Payments Year Four		19,500
Principal Payments Year Five		2,000
Senior Notes 6.625% Due 2021 [Member]
Debt Instrument [Line Items]
Aggregate principal amount		$ 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
Debt Instrument, Subjective Acceleration Clause		If an event of default occurs under the Unit credit agreement that accelerates the maturity of at least $25.0 million of borrowings, then it will cause a default under the 2011 Indenture which may in turn accelerate the maturity of the Notes.
Unit Credit Agreement [Member]
Debt Instrument [Line Items]
Credit facility maturity date		October 18, 2023
Credit Facility Maximum Credit Amount						$ 1,000,000
Commitment fee percentage under credit facility		0.375%
Origination, agency and syndication fees		$ 3,300
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
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		As of December 31, 2019, we were in compliance with these covenants.
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				$ 275,000	$ 425,000
Unit Credit Agreement [Member] | Line Of Credit Facility Commitment Amount | Subsequent Event
Debt Instrument [Line Items]
Credit facility current credit amount			$ 200,000
Unit Credit Agreement [Member] | Line Of Credit Facility Lender Determined Amount
Debt Instrument [Line Items]
Credit facility current credit amount				$ 275,000
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]
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 fees		$ 1,700
Covenant Compliance		As of December 31, 2019, Superior complied with these 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)