Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income [Roll Forward]
Balance. beginning of period	$ 5,420	$ (1,096)
Other comprehensive income before reclassifications:
Change in fair value of derivatives		6,683
Income tax effect		(2,079)
Net of tax		4,604
Amounts reclassified from accumulated other comprehensive income:
Oil and gas sales		3,044
Income tax effect		(1,132)
Net of tax		1,912
Net other comprehensive income		6,516
Balance, end of period	947	5,420
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income [Roll Forward]
Balance. beginning of period	5,420	(688)
Other comprehensive income before reclassifications:
Change in fair value of derivatives	9,991	6,683
Income tax effect	(3,716)	(2,487)
Net of tax	6,275	4,196
Amounts reclassified from accumulated other comprehensive income:
Oil and gas sales	(17,114)	3,044
Income tax effect	6,366	(1,132)
Net of tax	(10,748)	1,912
Net other comprehensive income	(4,473)	6,108
Balance, end of period	947	5,420
Change in Valuation Allowance
Accumulated Other Comprehensive Income [Roll Forward]
Balance. beginning of period	$ 0	(408)
Other comprehensive income before reclassifications:
Income tax effect		408
Net of tax		408
Amounts reclassified from accumulated other comprehensive income:
Income tax effect		0
Net of tax		0
Net other comprehensive income		408
Balance, end of period		$ 0