Impairments - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) Compressor	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($) Rigs
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of oil and natural gas properties	$ 5,015	$ 0	$ 9,991	$ 0
Effects of Cash Flow Hedges Considered in Calculation Ceiling Limitation, Amount	190		190
Impairments of fixed assets and other	84	40	88	60
Gain (Loss) on Contract Termination	(3)		$ (7)
Contractual Dispute [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other	47
Note Receivable [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other	13
Net Acreage Shortfall [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Other Cost and Expense, Operating		$ 22
Natural Gas Compressors [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other	$ 21
Equipment, Number of Units | Compressor	466
Drilling Rigs [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other				15
Gain (Loss) on Contract Termination				$ (8)
Leased Equipment Purchased | Rigs				31
Payments to Acquire Property, Plant, and Equipment				$ 140