Impairments (Note)	3 Months Ended
Mar. 31, 2015
Asset Impairment Charges [Abstract]
Asset Impairment Charges [Text Block]	Impairments Impairments of Oil and Natural Gas Properties Our oil and natural gas properties are subject to quarterly full cost ceiling tests. Under the ceiling test, capitalized costs, less accumulated amortization and related deferred income taxes, may not exceed an amount equal to the sum of the present value of estimated future net revenues (adjusted for cash flow hedges) less estimated future expenditures to be incurred in developing and producing the proved reserves, less any related income tax effects. Estimated future net revenues for the quarterly ceiling limit are calculated using the average of commodity prices on the first day of the month over the trailing 12-month period. In the Current Quarter, capitalized costs of oil and natural gas properties exceeded the ceiling, resulting in an impairment in the carrying value of our oil and natural gas properties of $4.976 billion. Cash flow hedges as of March 31, 2015, which related to future periods, increased the ceiling test impairment by $195 million. Based on the first-day-of the-month prices we have received over the 11 months ended May 1, 2015, we expect to record another material write-down in the carrying value of our oil and natural gas properties in the second quarter of 2015. Further material write-downs in subsequent quarters will occur if the trailing 12-month commodity prices continue to fall as compared to the commodity prices used in prior quarters. Impairments of Fixed Assets and Other Contract Termination Charges. In the Current Quarter, as a result of reductions in our planned drilling activity in response to declines in oil and natural gas prices, we terminated contracts with drilling contractors and incurred charges of $4 million. Further contract termination charges in subsequent quarters will occur if commodity prices remain low or continue to decline. The contract termination charges are included in our exploration and production operating segment. Oilfield Services Equipment. In the Prior Quarter, we purchased 20 leased rigs and equipment from various lessors for an aggregate purchase price of $77 million. In connection with these purchases, we paid $8 million in early lease termination costs, which are included in impairments of fixed assets and other in the condensed consolidated statement of operations. In addition, we recognized an impairment loss of approximately $12 million related to leasehold improvements associated with these assets. The drilling rigs and equipment are included in our former oilfield services operating segment. Nonrecurring Fair Value Measurements. Fair value measurements for certain of the impairments discussed above were based on recent sales information for comparable assets. As the fair value was estimated using the market approach based on recent prices from orderly sales transactions for comparable assets between market participants, the values were classified as Level 2 in the fair value hierarchy. As some inputs used were not observable in the market, these values were classified as Level 3 in the fair value hierarchy.

Impairments

Impairments of Oil and Natural Gas Properties

Our oil and natural gas properties are subject to quarterly full cost ceiling tests. Under the ceiling test, capitalized costs, less accumulated amortization and related deferred income taxes, may not exceed an amount equal to the sum of the present value of estimated future net revenues (adjusted for cash flow hedges) less estimated future expenditures to be incurred in developing and producing the proved reserves, less any related income tax effects. Estimated future net revenues for the quarterly ceiling limit are calculated using the average of commodity prices on the first day of the month over the trailing 12-month period. In the Current Quarter, capitalized costs of oil and natural gas properties exceeded the ceiling, resulting in an impairment in the carrying value of our oil and natural gas properties of $4.976 billion. Cash flow hedges as of March 31, 2015, which related to future periods, increased the ceiling test impairment by $195 million. Based on the first-day-of the-month prices we have received over the 11 months ended May 1, 2015, we expect to record another material write-down in the carrying value of our oil and natural gas properties in the second quarter of 2015. Further material write-downs in subsequent quarters will occur if the trailing 12-month commodity prices continue to fall as compared to the commodity prices used in prior quarters.

Impairments of Fixed Assets and Other

Contract Termination Charges. In the Current Quarter, as a result of reductions in our planned drilling activity in response to declines in oil and natural gas prices, we terminated contracts with drilling contractors and incurred charges of $4 million. Further contract termination charges in subsequent quarters will occur if commodity prices remain low or continue to decline. The contract termination charges are included in our exploration and production operating segment.

Oilfield Services Equipment. In the Prior Quarter, we purchased 20 leased rigs and equipment from various lessors for an aggregate purchase price of $77 million. In connection with these purchases, we paid $8 million in early lease termination costs, which are included in impairments of fixed assets and other in the condensed consolidated statement of operations. In addition, we recognized an impairment loss of approximately $12 million related to leasehold improvements associated with these assets. The drilling rigs and equipment are included in our former oilfield services operating segment.

Nonrecurring Fair Value Measurements. Fair value measurements for certain of the impairments discussed above were based on recent sales information for comparable assets. As the fair value was estimated using the market approach based on recent prices from orderly sales transactions for comparable assets between market participants, the values were classified as Level 2 in the fair value hierarchy. As some inputs used were not observable in the market, these values were classified as Level 3 in the fair value hierarchy.