Consolidated Statements of Operations (Audited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Natural gas, NGL and crude oil sales	$ 103,193	$ 104,483	$ 96,928	$ 74,109	$ 99,857	$ 120,526	$ 131,017	$ 120,013	$ 378,713	$ 471,413	$ 340,795
Sales from natural gas marketing	2,584	2,580	2,523	3,233	8,922	13,297	22,415	26,937	10,920	71,571	69,787
Commodity price risk management gain (loss), net	62,013	123,549	(49,041)	66,662	297,643	90,213	(52,643)	(24,909)	203,183	310,304	(23,919)
Well operations, pipeline income and other	844	488	550	628	1,269	520	514	616	2,510	2,919	6,002
Total revenues	168,634	231,100	50,960	144,632	407,691	224,556	101,303	122,657	595,326	856,207	392,665
Costs, expenses and other:
Lease operating expenses	14,244	13,824	12,639	16,285	11,050	11,020	11,961	8,371	56,992	42,402	33,817
Production taxes	5,237	5,476	3,837	3,893	2,950	8,724	7,551	6,390	18,443	25,615	21,758
Transportation, gathering and processing expenses	3,567	3,938	1,308	1,338	1,331	1,208	818	1,235	10,151	4,592	5,152
Cost of natural gas marketing	2,842	2,781	2,836	3,258	9,370	13,347	22,428	26,870	11,717	72,015	70,084
Exploration expense	290	252	275	285	174	190	276	307	1,102	947	6,334
Impairment of natural gas and crude oil properties	413	154,031	4,404	2,772	161,914	1,962	2,019	952	161,620	166,847	52,873
General and administrative expense	27,908	20,278	20,728	21,045	20,989	36,328	41,713	24,529	89,959	123,559	63,715
Depreciation, depletion and amortization	96,385	80,947	70,106	55,820	50,363	49,640	49,636	42,889	303,258	192,528	115,624
Accretion of asset retirement obligations	1,551	1,594	1,588	1,560	873	861	840	841	6,293	3,415	4,566
(Gain) loss on sale of Leaseholds	(83)	(74)	(207)	(21)	(70)	21	(23)	579	(385)	507	2,022
Total cost, expenses and other	152,354	283,047	117,514	106,235	258,944	123,301	137,219	112,963	659,150	632,427	375,945
Income from operations	16,280	(51,947)	(66,554)	38,397	148,747	101,255	(35,916)	9,694	(63,824)	223,780	16,720
Interest expense	(12,187)	(12,092)	(11,567)	(11,725)	(11,643)	(11,821)	(12,195)	(12,183)	(47,571)	(47,842)	(50,143)
Interest income	1,181	1,378	1,135	1,113	981	39	83	187	4,807	1,290	460
Income (loss) from continuing operations before income taxes	5,274	(62,661)	(76,986)	27,785	138,085	89,473	(48,028)	(2,302)	(106,588)	177,228	(32,963)
Provision for income taxes	(2,252)	21,167	30,116	(10,723)	(54,115)	(35,396)	18,650	894	38,308	(69,967)	11,852
Income (loss) from continuing operations	3,022	(41,494)	(46,870)	17,062	83,970	54,077	(29,378)	(1,408)	(68,280)	107,261	(21,111)
Income (loss) from discontinued operations, net of tax	0	0	0	0	47,782	(80)	1,191	(719)	0	48,174	(1,190)
Net income (loss)	$ 3,022	$ (41,494)	$ (46,870)	$ 17,062	$ 131,752	$ 53,997	$ (28,187)	$ (2,127)	$ (68,280)	$ 155,435	$ (22,301)
Basic
Income (loss) from continuing operations	$ 0.08	$ (1.04)	$ (1.17)	$ 0.47	$ 2.34	$ 1.51	$ (0.82)	$ (0.04)	$ (1.74)	$ 3.00	$ (0.65)
Income (loss) from discontinued operations	0.00	0.00	0.00	0.00	1.33	0.00	0.03	(0.02)	0.00	1.34	(0.04)
Net income (loss) attributable to shareholders	0.08	(1.04)	(1.17)	0.47	3.67	1.51	(0.79)	(0.06)	(1.74)	4.34	(0.69)
Diluted
Income (loss) from continuing operations	0.07	(1.04)	(1.17)	0.46	2.32	1.47	(0.82)	(0.04)	(1.74)	2.93	(0.65)
Income (loss) from discontinued operations	0.00	0.00	0.00	0.00	1.32	0.00	0.03	(0.02)	0.00	1.31	(0.04)
Net income (loss) attributable to shareholders	$ 0.07	$ (1.04)	$ (1.17)	$ 0.46	$ 3.64	$ 1.47	$ (0.79)	$ (0.06)	$ (1.74)	$ 4.24	$ (0.69)
Weighted-average common shares outstanding:
Basic	40,094	40,085	40,035	36,349	35,847	35,834	35,762	35,690	39,153	35,784	32,426
Diluted	41,264	40,085	40,035	36,981	36,146	36,828	35,762	35,690	39,153	36,678	32,426