Condensed Consolidating Financial Information - (Cash flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net cash provided by operating activities	$ 134,409	$ 209,201	$ 217,198
Cash flows from investing activities:
Oil and natural gas property additions	(332,771)	(548,841)	(360,080)
Oil and natural gas property acquisitions		(36,772)
Cash received in Forest acquisition		134,887
Cash received from insurance proceeds			604
Gas processing equipment additions	(1,497)	(2,988)	(4,014)
Other asset additions	(1,877)	(2,242)	(2,075)
Cash received from sale of assets	6,749	17,342	171,756
Net cash used in investing activities	(329,396)	(438,614)	(193,809)
Cash flows from financing activities:
Borrowings under senior secured revolving credit facility	425,987	1,209,835	193,000
Borrowings under second lien term loan			153,500
Debt repayments for the senior secured revolving credit facility	(24,324)	(969,835)	(348,000)
Debt issuance costs	(1,110)	(19,156)	(6,261)
Distributions			(10,000)
Shares repurchased	(181)
Net cash provided by (used in) financing activities	400,372	220,844	(17,761)
Net increase (decrease) in cash and cash equivalents	205,385	(8,569)	5,628
Cash and cash equivalents, beginning of period	3,252	11,821	6,193
Cash and cash equivalents, end of period	208,637	3,252	11,821
Eliminations
Cash flows from investing activities:
Advances to subsidiaries	1,258	265	1,470
Net cash used in investing activities	1,258	265	1,470
Cash flows from financing activities:
Proceeds from subsidiaries	(1,258)	(265)	(1,470)
Net cash provided by (used in) financing activities	(1,258)	(265)	(19,231)
Parent Company Issuer | Reportable legal entity
Cash flows from operating activities:
Net cash provided by operating activities	134,409	209,201	217,198
Cash flows from investing activities:
Oil and natural gas property additions	(332,771)	(548,841)	(360,080)
Oil and natural gas property acquisitions		(36,772)
Cash received in Forest acquisition		134,887
Cash received from insurance proceeds			604
Gas processing equipment additions	(1,497)	(2,988)	(4,014)
Other asset additions	(1,877)	(2,242)	(2,075)
Cash received from sale of assets	6,749	17,342	171,756
Advances to subsidiaries			(1,470)
Net cash used in investing activities	(329,396)	(438,614)	(195,279)
Cash flows from financing activities:
Borrowings under senior secured revolving credit facility	425,987	1,209,835	193,000
Borrowings under second lien term loan			153,500
Debt repayments for the senior secured revolving credit facility	(24,324)	(969,835)	(348,000)
Debt issuance costs	(1,110)	(19,156)	(6,261)
Distributions			(10,000)
Shares repurchased	(181)
Proceeds from subsidiaries	1,258	(265)
Net cash provided by (used in) financing activities	401,630	221,109	(17,761)
Net increase (decrease) in cash and cash equivalents	206,643	(8,304)	4,158
Cash and cash equivalents, beginning of period	1,993	10,297	6,139
Cash and cash equivalents, end of period	208,636	1,993	10,297
Guarantor Subsidiaries | Reportable legal entity
Cash flows from investing activities:
Advances to subsidiaries	(1,258)	(265)
Net cash used in investing activities	(1,258)	(265)
Cash flows from financing activities:
Proceeds from subsidiaries			1,470
Net cash provided by (used in) financing activities			1,470
Net increase (decrease) in cash and cash equivalents	(1,258)	(265)	1,470
Cash and cash equivalents, beginning of period	1,259	1,524	54
Cash and cash equivalents, end of period	$ 1	$ 1,259	$ 1,524