Consolidated Statements of Operations (Audited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues:
Natural gas, NGL and crude oil sales	$ 120,286	$ 82,136	$ 77,537	$ 79,439	$ 67,773	$ 52,291	$ 51,342	$ 66,955	$ 359,398	$ 238,361	$ 223,297
Sales from natural gas marketing	21,092	16,946	18,079	13,670	14,199	11,178	8,613	11,381	69,787	45,371	63,470
Commodity price risk management gain (loss), net	(2,636)	(23,638)	24,724	(22,355)	14,052	(31,943)	38,729	11,501	(23,905)	32,339	46,090
Well operations, pipeline income and other	2,325	1,672	965	1,072	1,115	1,194	1,056	1,169	6,034	4,534	4,432
Total revenues	141,067	77,116	121,305	71,826	97,139	32,720	99,740	91,006	411,314	320,605	337,289
Costs, expenses and other:
Production costs	22,299	19,057	16,176	15,858	13,594	15,797	12,373	12,936	73,390	54,700	44,832
Cost of natural gas marketing	21,156	17,127	18,065	13,736	14,182	11,260	8,490	11,091	70,084	45,023	62,831
Exploration expense	1,883	2,030	1,437	1,689	14,875	1,773	2,374	1,872	7,039	20,894	5,734
Impairment of natural gas and crude oil properties	1,002	4,472	1,502	46,459	4,563	388	356	588	53,435	5,895	2,301
General and administrative expense	16,991	16,080	15,783	15,115	16,019	13,710	14,378	14,708	63,969	58,815	61,454
Depreciation, depletion and amortization	40,641	30,870	27,800	27,949	24,906	22,121	23,839	27,912	127,260	98,778	87,633
Accretion of asset retirement obligations	1,080	1,186	1,172	1,148	1,127	1,101	732	727	4,586	3,687	1,398
Gain on sale of Leaseholds	2,151	(712)	(9)	(38)	(445)	(1,508)	(2,246)	(154)	1,392	(4,353)	(196)
Total cost, expenses and other	107,203	90,110	81,926	121,916	88,821	64,642	60,296	69,680	401,155	283,439	265,987
Income (loss) from operations	33,864	(12,994)	39,379	(50,090)	8,318	(31,922)	39,444	21,326	10,159	37,166	71,302
Loss on extinguishment of debt					(23,283)	0	0	0	0	(23,283)	0
Interest expense	(12,943)	(12,509)	(13,089)	(13,357)	(16,430)	(11,360)	(10,053)	(10,444)	(51,898)	(48,287)	(36,985)
Interest income	337	130	3	0	3	3	0	2	470	8	47
Income (loss) from continuing operations before income taxes	21,258	(25,373)	26,293	(63,447)	(31,392)	(43,279)	29,391	10,884	(41,269)	(34,396)	34,364
Provision for income taxes	(8,059)	10,155	(9,791)	22,492	11,766	15,268	(10,213)	(4,120)	14,797	12,701	(11,800)
Income (loss) from continuing operations	13,199	(15,218)	16,502	(40,955)	(19,626)	(28,011)	19,178	6,764	(26,472)	(21,695)	22,564
Income (loss) from discontinued operations, net of tax	0	(782)	3,416	1,537	(106,549)	(4,632)	(6,907)	9,071	4,171	(109,017)	(9,127)
Net income (loss)	$ 13,199	$ (16,000)	$ 19,918	$ (39,418)	$ (126,175)	$ (32,643)	$ 12,271	$ 15,835	$ (22,301)	$ (130,712)	$ 13,437
Basic
Income (loss) from continuing operations	$ 0.37	$ (0.46)	$ 0.55	$ (1.35)	$ (0.65)	$ (0.93)	$ 0.72	$ 0.29	$ (0.82)	$ (0.78)	$ 0.96
Income (loss) from discontinued operations	$ 0.00	$ (0.02)	$ 0.11	$ 0.05	$ (3.52)	$ (0.15)	$ (0.26)	$ 0.38	$ 0.13	$ (3.94)	$ (0.39)
Net income (loss) attributable to shareholders	$ 0.37	$ (0.48)	$ 0.66	$ (1.30)	$ (4.17)	$ (1.08)	$ 0.46	$ 0.67	$ (0.69)	$ (4.72)	$ 0.57
Diluted
Income (loss) from continuing operations	$ 0.36	$ (0.46)	$ 0.53	$ (1.35)	$ (0.65)	$ (0.93)	$ 0.72	$ 0.28	$ (0.82)	$ (0.78)	$ 0.95
Income (loss) from discontinued operations	$ 0.00	$ (0.02)	$ 0.11	$ 0.05	$ (3.52)	$ (0.15)	$ (0.26)	$ 0.38	$ 0.13	$ (3.94)	$ (0.39)
Net income (loss) attributable to shareholders	$ 0.36	$ (0.48)	$ 0.64	$ (1.30)	$ (4.17)	$ (1.08)	$ 0.46	$ 0.66	$ (0.69)	$ (4.72)	$ 0.56
Weighted-average common shares outstanding:
Basic	35,620	33,413	30,332	30,270	30,233	30,214	26,597	23,609	32,426	27,677	23,521
Diluted	36,836	33,413	31,014	30,270	30,233	30,214	26,728	23,889	32,426	27,677	23,871