Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accumulated other Comprehensive Income [Roll Forward]
Balance, beginning of period	$ (3,654)	$ 1,418	$ (1,096)	$ 521
Change in fair value of derivatives	5,293	110	(3,510)	1,047
Income tax effect	(609)	(41)	(609)	(389)
Other comprehensive loss before reclassifications	4,684	69	(4,119)	658
Oil and gas sales	(240)	(234)	6,005	257
Income tax effect	89	87	89	(96)
Amounts reclassified from accumulated other comprehensive income (loss)	(151)	(147)	6,094	161
Net other comprehensive income	4,533	(78)	1,975	819
Balance, end of period	879	1,340	879	1,340
Gains and Losses on Cash Flow Hedges
Accumulated other Comprehensive Income [Roll Forward]
Balance, beginning of period	(2,294)	1,418	(688)	521
Change in fair value of derivatives	5,293	110	(3,510)	1,047
Income tax effect	(1,969)	(41)	1,395	(389)
Other comprehensive loss before reclassifications	3,324	69	(2,115)	658
Oil and gas sales	(240)	(234)	6,005	257
Income tax effect	89	87	(2,323)	(96)
Amounts reclassified from accumulated other comprehensive income (loss)	(151)	(147)	3,682	161
Net other comprehensive income	3,173	(78)	1,567	819
Balance, end of period	879	1,340	879	1,340
Change in Valuation Allowance
Accumulated other Comprehensive Income [Roll Forward]
Balance, beginning of period	(1,360)	0	(408)	0
Change in fair value of derivatives		0		0
Income tax effect	1,360	0	(2,004)	0
Other comprehensive loss before reclassifications	1,360	0	(2,004)	0
Oil and gas sales		0		0
Income tax effect	0	0	2,412	0
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	2,412	0
Net other comprehensive income	1,360	0	408	0
Balance, end of period	$ 0	$ 0	$ 0	$ 0