Subsequent Events Subsequent Events (Notes)	9 Months Ended
Sep. 30, 2016
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events On October 5, 2016, we issued in a private placement $1.25 billion principal amount of unsecured 5.5% Convertible Senior Notes due 2026. The notes will be convertible, under certain specified circumstances, into cash, common stock or a combination of cash and common stock, at our election. We are using the net proceeds for general corporate purposes, which may include debt repurchases and the repayment of our revolving credit facility and senior notes with near term maturities as they become due. Additionally, on October 5, 2016, we completed private exchanges of an aggregate of approximately 110.3 million shares of our common stock for (i) 134,000 shares of 5.00% Cumulative Convertible Preferred Stock (Series 2005B), (ii) 606,271 shares of 5.75% Cumulative Convertible Preferred Stock and (iii) 553,007 shares of 5.75% Cumulative Convertible Preferred Stock (Series A). In October 2016, we repurchased in the open market approximately $105 million principal amount of our outstanding debt scheduled to mature or that could be put to us in 2017 and 2018 for $106 million. On October 18, 2016, we signed a letter of intent to restructure our natural gas gathering and service agreement in our Powder River Basin operating area with Williams Partners L.P. and Crestwood Equity Partners L.P. The restructured services are expected to replace the current cost-of-service arrangement and improve economics which support increased development across an expanded area of dedication in the region. Subject to board approvals from all three companies of the definitive agreement, the restructured services are to become effective January 1, 2017, for a 20-year term. On October 31, 2016, we conveyed our interests in the Barnett Shale operating area located in north central Texas and received from the buyer aggregate net proceeds of approximately $218 million. We simultaneously terminated most of our future commitments associated with this asset. We sold approximately 212,000 net developed and undeveloped acres and approximately 2,800 operated wells, which produced an average of approximately 59 mboe per day in the Current Quarter, along with other property and equipment. In connection with this disposition, we paid $334 million to terminate a natural gas gathering agreement associated with the Barnett Shale assets. Additionally, we may be required to pay up to an additional $70 million in respect of certain title and environmental contingencies.

Subsequent Events

On October 5, 2016, we issued in a private placement $1.25 billion principal amount of unsecured 5.5% Convertible Senior Notes due 2026. The notes will be convertible, under certain specified circumstances, into cash, common stock or a combination of cash and common stock, at our election. We are using the net proceeds for general corporate purposes, which may include debt repurchases and the repayment of our revolving credit facility and senior notes with near term maturities as they become due.

Additionally, on October 5, 2016, we completed private exchanges of an aggregate of approximately 110.3 million shares of our common stock for (i) 134,000 shares of 5.00% Cumulative Convertible Preferred Stock (Series 2005B), (ii) 606,271 shares of 5.75% Cumulative Convertible Preferred Stock and (iii) 553,007 shares of 5.75% Cumulative Convertible Preferred Stock (Series A).

In October 2016, we repurchased in the open market approximately $105 million principal amount of our outstanding debt scheduled to mature or that could be put to us in 2017 and 2018 for $106 million.

On October 18, 2016, we signed a letter of intent to restructure our natural gas gathering and service agreement in our Powder River Basin operating area with Williams Partners L.P. and Crestwood Equity Partners L.P. The restructured services are expected to replace the current cost-of-service arrangement and improve economics which support increased development across an expanded area of dedication in the region. Subject to board approvals from all three companies of the definitive agreement, the restructured services are to become effective January 1, 2017, for a 20-year term.

On October 31, 2016, we conveyed our interests in the Barnett Shale operating area located in north central Texas and received from the buyer aggregate net proceeds of approximately $218 million. We simultaneously terminated most of our future commitments associated with this asset. We sold approximately 212,000 net developed and undeveloped acres and approximately 2,800 operated wells, which produced an average of approximately 59 mboe per day in the Current Quarter, along with other property and equipment. In connection with this disposition, we paid $334 million to terminate a natural gas gathering agreement associated with the Barnett Shale assets. Additionally, we may be required to pay up to an additional $70 million in respect of certain title and environmental contingencies.