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Summary of Significant Accounting Policies Other (Details) (USD $) | 12 Months Ended |  |  |  |
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2013 Regency Gas Services, LLC [Member] | Dec. 31, 2012 Regency Gas Services, LLC [Member] | Dec. 31, 2011 Regency Gas Services, LLC [Member] | Dec. 31, 2013 Anadarko Petroleum Company [Member] | Dec. 31, 2013 Plains Marketing, LP [Member] | Dec. 31, 2012 Plains Marketing, LP [Member] | Dec. 31, 2012 Convertible Debt [Member] | Dec. 31, 2013 Convertible Debt [Member] | Dec. 31, 2010 Convertible Debt [Member] | Dec. 31, 2013 Line of Credit [Member] | Dec. 31, 2012 Line of Credit [Member]
Basis of Presentation and Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving credit facility | $ 0 | $ 340,000,000 |  |  |  |  |  |  |  |  |  |  | $ 0 | $ 340,000,000
Concentration of Credit Risk and Major Customers [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Major Customers | 3 | 2 | 1 |  |  |  |  |  |  |  |  |  |  |
Entity-Wide Revenue, Major Customer, Percentage |  |  |  | 26.00% | 21.00% | 18.00% | 16.00% | 12.00% | 13.00% |  |  |  |  |
Number of Counterparties Downgraded | 3 |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Derivative Counterparties | 10 |  |  |  |  |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property, Plant, and Equipment, Salvage Value | 57,500,000 | 64,400,000 |  |  |  |  |  |  |  |  |  |  |  |
Inventory, Net [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Raw Materials Inventory | 16,000,000 | 13,400,000 |  |  |  |  |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | three to thirty years |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill and Intangible Assets Disclosure [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible Assets, Net (Excluding Goodwill) | 10,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue Receipt, Days After Sale, Low End of Range | 30 |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue Receipt, Days After Sale, High End of Range | 90 |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Proved Properties [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of New York Mercantile Exchange Strip Pricing Used for Price Forecast | 5 |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of proved properties | 172,641,000 | 208,923,000 | 219,037,000 |  |  |  |  |  |  |  |  |  |  |
Abandonment and impairment of unproved properties | 46,105,000 | 16,342,000 | 7,367,000 |  |  |  |  |  |  |  |  |  |  |
Debt Instruments [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  |  |  |  |  |  |  | 3.50% | 3.50% | 3.50% |  |
Debt Instrument, Convertible, Conversion Price |  |  |  |  |  |  |  |  |  | $ 54.42 |  |  |  |
Debt Instrument, Principal Amount Denominator for Conversion into Common Stock |  |  |  |  |  |  |  |  |  | 1,000 |  |  |  |
Debt instrument convertible conversion rate |  |  |  |  |  |  |  |  |  | 864,106 |  |  |  |
Capitalization of Development and Implementation of Internal Use Software | $ 11,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |

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