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Price-Risk Management Price-Risk Management (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) bbl MMBTU $ / MMBTU $ / Boe	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) on Price Risk Derivatives, Net \| $	$ (4,000)	$ (6,400)
Cash Received (Paid) On Settlements of Derivative Contracts \| $	1,077	$ 977
Receivables for Settled Derivatives \| $	1,000		$ 700
Payables for Settled Derivatives \| $	200		2,200
Derivative, Fair Value, Net \| $	5,600		13,000
Other Current Assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Fair Value, Gross Asset \| $	8,300		15,300
Other Noncurrent Assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Fair Value, Gross Asset \| $	4,000		4,300
Other Current Liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Liability, Fair Value, Gross Liability \| $	4,600		2,800
Other Noncurrent Liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Liability, Fair Value, Gross Liability \| $	$ 2,200		$ 3,700
Swap [Member] \| Oil Derivative Swaps [Member] \| Second Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	157,450
Derivative, Swap Type, Fixed Price \| $ / Boe	57.30
Swap [Member] \| Oil Derivative Swaps [Member] \| Third Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	176,500
Derivative, Swap Type, Fixed Price \| $ / Boe	57.98
Swap [Member] \| Oil Derivative Swaps [Member] \| Fourth Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	172,500
Derivative, Swap Type, Fixed Price \| $ / Boe	58.07
Swap [Member] \| Oil Derivative Swaps [Member] \| First Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	149,300
Derivative, Swap Type, Fixed Price \| $ / Boe	57.32
Swap [Member] \| Oil Derivative Swaps [Member] \| Second Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	100,350
Derivative, Swap Type, Fixed Price \| $ / Boe	56.38
Swap [Member] \| Oil Derivative Swaps [Member] \| Third Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	97,200
Derivative, Swap Type, Fixed Price \| $ / Boe	56.49
Swap [Member] \| Oil Derivative Swaps [Member] \| Fourth Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	72,000
Derivative, Swap Type, Fixed Price \| $ / Boe	52.29
Swap [Member] \| Oil Derivative Swaps [Member] \| First Quarter 2021 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	56,175
Derivative, Swap Type, Fixed Price \| $ / Boe	55.23
Swap [Member] \| Natural Gas Derivative Swaps [Member] \| Second Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	12,130,000
Derivative, Swap Type, Fixed Price	2.80
Swap [Member] \| Natural Gas Derivative Swaps [Member] \| Third Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	12,680,000
Derivative, Swap Type, Fixed Price	2.81
Swap [Member] \| Natural Gas Derivative Swaps [Member] \| Fourth Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	11,486,000
Derivative, Swap Type, Fixed Price	2.89
Swap [Member] \| Natural Gas Derivative Swaps [Member] \| First Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	6,280,000
Derivative, Swap Type, Fixed Price	2.87
Swap [Member] \| Natural Gas Derivative Swaps [Member] \| Second Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	3,688,000
Derivative, Swap Type, Fixed Price	2.76
Swap [Member] \| Natural Gas Derivative Swaps [Member] \| Third Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	3,585,000
Derivative, Swap Type, Fixed Price	2.76
Swap [Member] \| Natural Gas Derivative Swaps [Member] \| Fourth Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	3,362,000
Derivative, Swap Type, Fixed Price	2.77
Swap [Member] \| Natural Gas Liquid Derivative [Member] \| Second Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	180,000
Derivative, Swap Type, Fixed Price	27.93
Swap [Member] \| Natural Gas Liquid Derivative [Member] \| Third Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	180,000
Derivative, Swap Type, Fixed Price	27.93
Swap [Member] \| Natural Gas Liquid Derivative [Member] \| Fourth Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	180,000
Derivative, Swap Type, Fixed Price	27.93
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Second Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	14,477,500
Derivative, Basis Swap Type, Fixed Price	0.05
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Third Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	14,625,000
Derivative, Basis Swap Type, Fixed Price	0.04
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Fourth Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	14,625,000
Derivative, Basis Swap Type, Fixed Price	(0.02)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| First Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	11,739,000
Derivative, Basis Swap Type, Fixed Price	(0.03)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Second Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	11,739,000
Derivative, Basis Swap Type, Fixed Price	(0.04)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Third Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	11,868,000
Derivative, Basis Swap Type, Fixed Price	(0.03)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Fourth Quarter 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	11,868,000
Derivative, Basis Swap Type, Fixed Price	(0.04)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| First Quarter 2021 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	7,200,000
Derivative, Basis Swap Type, Fixed Price	(0.003)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Second Quarter 2021 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	7,280,000
Derivative, Basis Swap Type, Fixed Price	(0.003)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Third Quarter 2021 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	7,360,000
Derivative, Basis Swap Type, Fixed Price	(0.003)
Basis Swap [Member] \| Natural Gas Basis Derivative Swaps [Member] \| Fourth Quarter 2021 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	7,360,000
Derivative, Basis Swap Type, Fixed Price	(0.003)
Basis Swap [Member] \| Oil Basis Derivative [Member] \| Second Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	45,000
Derivative, Basis Swap Type, Fixed Price	4.65
Basis Swap [Member] \| Oil Basis Derivative [Member] \| Third Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	45,000
Derivative, Basis Swap Type, Fixed Price	4.65
Basis Swap [Member] \| Oil Basis Derivative [Member] \| Fourth Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| bbl	45,000
Derivative, Basis Swap Type, Fixed Price	4.65
Forward Contracts [Member] \| Natural Gas Derivative Swaps [Member] \| Second Quarter 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	300,000
Derivative, Average Floor Price	2.90
Derivative, Average Cap Price	3.15
Forward Contracts [Member] \| Natural Gas Derivative Swaps [Member] \| First Quarter 2021 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Oil and Gas Production Hedged Volumes \| MMBTU	4,354,800
Derivative, Average Floor Price	2.50
Derivative, Average Cap Price	3.52