Impairments Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Significant Acquisitions and Disposals [Line Items]
Impairment of natural gas and oil properties	$ 0	$ 3,315	$ 0	$ 3,315
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	44
Effects of Cash Flow Hedges Considered in Calculation Ceiling Limitation, Amount	279		279
Repurchase of Rigs [Member]
Significant Acquisitions and Disposals [Line Items]
Equipment Owned		22
Land and Building [Member]
Significant Acquisitions and Disposals [Line Items]
Impairment of Long-Lived Assets to be Disposed of			28	227
Land and Building [Member] | Assets Held-for-sale [Member]
Significant Acquisitions and Disposals [Line Items]
Impairment of Long-Lived Assets to be Disposed of			31
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down			138
Drilling Rigs [Member]
Significant Acquisitions and Disposals [Line Items]
Impairment of Long-Lived Assets to be Disposed of	24	6		20
Equipment Owned	8
Payments to Acquire Property, Plant, and Equipment				53
Drilling Rigs [Member] | Repurchase of Rigs [Member]
Significant Acquisitions and Disposals [Line Items]
Impairment of Long-Lived Assets to be Disposed of		25
Drilling Rigs [Member] | Assets Held-for-sale [Member]
Significant Acquisitions and Disposals [Line Items]
Equipment Owned	7.0
Tubular Goods [Member]
Significant Acquisitions and Disposals [Line Items]
Impairment of Long-Lived Assets to be Disposed of				9
Gas Gathering and Processing Equipment [Member] | Assets Held-for-sale [Member]
Significant Acquisitions and Disposals [Line Items]
Impairment of Long-Lived Assets to be Disposed of	26
Gas Gathering and Processing Equipment [Member] | Assets Held-for-Use [Member]
Significant Acquisitions and Disposals [Line Items]
Impairment of Long-Lived Assets to be Disposed of	$ 18