Income Taxes--Narrative (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Line Items]
Net current deferred tax asset	$ 9,260	$ 0
Net current deferred tax liability	0	(26,872)
Deferred tax asset - account receivable	434	245
Change in valuation allowance on deferred tax asset	1,473
Derivative
Income Tax Disclosure [Line Items]
Net current deferred tax asset	2,252
Net current deferred tax liability		(33,066)
Asset Retirement Obligation Costs
Income Tax Disclosure [Line Items]
Net current deferred tax asset	656	1,015
Internal Revenue Service (IRS)
Income Tax Disclosure [Line Items]
Operating loss carryforwards	357,000
Internal Revenue Service (IRS) | No Expiration
Income Tax Disclosure [Line Items]
Operating loss carryforwards	8,000
State and Local Jurisdiction
Income Tax Disclosure [Line Items]
Operating loss carryforwards	335,000
Operating loss carryforwards valuation allowance	$ (262,000)