Impairment of Natural Gas and Crude Oil Properties (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
Continuing Operations:
Impairment of proved properties	$ 0	$ 3,750	$ 0	$ 48,750
Impairment of individually significantly unproved properties	0	0	0	517
Amortization of Individually Insignificant Unproved Properties	1,085	486	2,843	2,527
Impairment of other properties	778	0	778	0
Total continuing operations	1,863	4,236	3,621	51,794
Discontinued operations:
Impairment of individually significant unproved properties - discontinued operations	0	154	0	462
Amortization of Individually Insignificant Unproved Properties - discontinued operations	274	82	433	180
Total discontinued operations	274	236	433	642
Total impairment of crude oil and natural gas properties	2,137	4,472	4,054	52,436
Shallow Upper Devonian properties [Member]
Continuing Operations:
Impairment of proved properties		$ 3,800		$ 45,000