Income Taxes--Narrative (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Line Items]
Deferred income taxes	$ (60,728,000)	$ 9,260,000
Deferred tax asset - account receivable	336,000	434,000
Derivative [Member]
Income Tax Disclosure [Line Items]
Deferred income taxes	67,352,000	2,252,000
Asset Retirement Obligation Costs [Member]
Income Tax Disclosure [Line Items]
Deferred income taxes	1,553,000	656,000
Internal Revenue Service (IRS) [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards	347,000,000
Operating loss carryforwards, not subject to expiration	11,000,000
State and Local Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards	386,000,000
Operating loss carryforwards valuation allowance	$ (262,000,000)