Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated other Comprehensive Income [Roll Forward]
Balance, beginning of period		$ (3,654)	$ 5,420	$ (1,096)
Change in fair value of derivatives		5,293		(3,510)
Income tax effect		(609)		(609)
Net of tax		4,684		(4,119)
Oil and gas sales		(240)		6,005
Income tax effect		89		89
Net of tax		(151)		6,094
Net other comprehensive income (loss)		4,533		1,975
Balance, end of period	$ 3,554	879	3,554	879
Gains and Losses on Cash Flow Hedges
Accumulated other Comprehensive Income [Roll Forward]
Balance, beginning of period	3,564	(2,294)	5,420	(688)
Change in fair value of derivatives	4,077	5,293	7,523	(3,510)
Income tax effect	(1,517)	(1,969)	(2,799)	1,395
Net of tax	2,560	3,324	4,724	(2,115)
Oil and gas sales	(4,093)	(240)	(10,494)	6,005
Income tax effect	1,523	89	3,904	(2,323)
Net of tax	(2,570)	(151)	(6,590)	3,682
Net other comprehensive income (loss)	(10)	3,173	(1,866)	1,567
Balance, end of period	$ 3,554	879	$ 3,554	879
Change in Valuation Allowance
Accumulated other Comprehensive Income [Roll Forward]
Balance, beginning of period		(1,360)		(408)
Change in fair value of derivatives		0		0
Income tax effect		1,360		(2,004)
Net of tax		1,360		(2,004)
Oil and gas sales		0		0
Income tax effect		0		2,412
Net of tax		0		2,412
Net other comprehensive income (loss)		1,360		408
Balance, end of period		$ 0		$ 0