Supplemental Guarantor Condensed Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Sep. 30, 2015		Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 1,702		$ 1,843	$ 2,078	$ 746
Current Assets	364		2
Advances to parent and affiliates	6		8
Trade accounts receivable – net	770		$ 588
Income taxes receivable	0
Inventories	388		$ 468
Commodity and other derivative contractual assets	393		492
Other current assets	53		68
Total current assets	3,676		3,469
Noncurrent Assets	506		901
Investments	919		941
Property, plant and equipment – net	9,985		12,288
Advances to parent and affiliates	3		7
Goodwill	952	[1]	2,352
Identifiable intangible assets – net	1,174		1,336
Commodity and other derivative contractual assets	30		5
Accumulated deferred income taxes	0		0
Other noncurrent assets	40		34
Total assets	17,285		21,333
Current liabilities:
Advances from Parent			0
Borrowings under debtor-in-possession credit facility (Note 8)	1,425		0
Long-term debt due currently	32		35
Trade accounts payable	361		382
Trade accounts and other payables to affiliates	177		165
Commodity and other derivative contractual liabilities	160		316
Margin deposits related to commodity positions	126		26
Accumulated deferred income taxes	111		114
Accrued income taxes payable to parent	0		16
Accrued taxes other than income	85		107
Accrued interest	115		117
Other current liabilities	264		264
Total current liabilities	2,856		1,542
Accumulated deferred income taxes	212		1,022
Commodity and other derivative contractual liabilities	4		1
Notes or other liabilities due affiliates	0
Borrowings under debtor-in-possession credit facility (Note 8)	0		1,425
Long-term debt, less amounts due currently (Note 8)	66		85
Liabilities subject to compromise (Note 9)	34,008		34,033
Other noncurrent liabilities and deferred credits	1,667		1,699
Total liabilities	38,813		39,807
Total membership interests	(21,528)		(18,474)	(13,418)	(12,268)
Total liabilities and membership interests	17,285		21,333
Parent Guarantor [Member]
Current assets:
Cash and cash equivalents	0		0	0	0
Current Assets	0		0
Advances to parent and affiliates	0		0
Trade accounts receivable – net	0		0
Income taxes receivable	1		0
Inventories	0		0
Commodity and other derivative contractual assets	0		0
Other current assets	0		0
Total current assets	1		0
Noncurrent Assets	0		0
Investments	(31,199)		(28,114)
Property, plant and equipment – net	0		0
Advances to parent and affiliates	0		0
Goodwill	0		0
Identifiable intangible assets – net	0		0
Commodity and other derivative contractual assets	0		0
Accumulated deferred income taxes	0		0
Other noncurrent assets	0		0
Total assets	(31,198)		(28,114)
Current liabilities:
Advances from Parent			8
Borrowings under debtor-in-possession credit facility (Note 8)	0
Long-term debt due currently	14		13
Trade accounts payable	0		0
Trade accounts and other payables to affiliates	0		2
Commodity and other derivative contractual liabilities	0		0
Margin deposits related to commodity positions	0		0
Accumulated deferred income taxes	24		24
Accrued income taxes payable to parent	0		0
Accrued taxes other than income	0		0
Accrued interest	1		0
Other current liabilities	0		0
Total current liabilities	39		47
Accumulated deferred income taxes	23		40
Commodity and other derivative contractual liabilities	0		0
Notes or other liabilities due affiliates	0
Borrowings under debtor-in-possession credit facility (Note 8)			0
Long-term debt, less amounts due currently (Note 8)	30		34
Liabilities subject to compromise (Note 9)	144		144
Other noncurrent liabilities and deferred credits	0		0
Total liabilities	236		265
Total membership interests	(31,434)		(28,379)
Total liabilities and membership interests	(31,198)		(28,114)
Issuer [Member]
Current assets:
Cash and cash equivalents	1,668		1,826	2,053	725
Current Assets	364		0
Advances to parent and affiliates	6		8
Trade accounts receivable – net	0		0
Income taxes receivable	487		176
Inventories	0		0
Commodity and other derivative contractual assets	0		0
Other current assets	3		9
Total current assets	2,528		2,019
Noncurrent Assets	506		901
Investments	7,819		10,845
Property, plant and equipment – net	17		34
Advances to parent and affiliates	3		7
Goodwill	952		2,352
Identifiable intangible assets – net	28		14
Commodity and other derivative contractual assets	0		0
Accumulated deferred income taxes	831		757
Other noncurrent assets	3		3
Total assets	12,687		16,932
Current liabilities:
Advances from Parent			1,171
Borrowings under debtor-in-possession credit facility (Note 8)	1,425
Long-term debt due currently	0		0
Trade accounts payable	14		7
Trade accounts and other payables to affiliates	0		7
Commodity and other derivative contractual liabilities	0		0
Margin deposits related to commodity positions	0		0
Accumulated deferred income taxes	43		47
Accrued income taxes payable to parent	0		0
Accrued taxes other than income	0		0
Accrued interest	113		116
Other current liabilities	40		37
Total current liabilities	1,635		1,385
Accumulated deferred income taxes	0		0
Commodity and other derivative contractual liabilities	0		0
Notes or other liabilities due affiliates	0
Borrowings under debtor-in-possession credit facility (Note 8)			1,425
Long-term debt, less amounts due currently (Note 8)	0		0
Liabilities subject to compromise (Note 9)	42,255		42,239
Other noncurrent liabilities and deferred credits	(4)		(3)
Total liabilities	43,886		45,046
Total membership interests	(31,199)		(28,114)
Total liabilities and membership interests	12,687		16,932
Other Guarantors [Member]
Current assets:
Cash and cash equivalents	23		16	24	16
Current Assets	0		2
Advances to parent and affiliates	0		1,179
Trade accounts receivable – net	770		588
Income taxes receivable	0		0
Inventories	388		468
Commodity and other derivative contractual assets	393		492
Other current assets	50		59
Total current assets	1,624		2,804
Noncurrent Assets	0		0
Investments	942		958
Property, plant and equipment – net	9,965		12,251
Advances to parent and affiliates	0		0
Goodwill	0		0
Identifiable intangible assets – net	1,146		1,322
Commodity and other derivative contractual assets	30		5
Accumulated deferred income taxes	0		0
Other noncurrent assets	37		31
Total assets	13,744		17,371
Current liabilities:
Advances from Parent			0
Borrowings under debtor-in-possession credit facility (Note 8)	0
Long-term debt due currently	18		22
Trade accounts payable	347		375
Trade accounts and other payables to affiliates	177		154
Commodity and other derivative contractual liabilities	160		316
Margin deposits related to commodity positions	126		26
Accumulated deferred income taxes	44		43
Accrued income taxes payable to parent	486		192
Accrued taxes other than income	85		107
Accrued interest	1		1
Other current liabilities	224		227
Total current liabilities	1,668		1,463
Accumulated deferred income taxes	197		944
Commodity and other derivative contractual liabilities	4		1
Notes or other liabilities due affiliates	0
Borrowings under debtor-in-possession credit facility (Note 8)			0
Long-term debt, less amounts due currently (Note 8)	36		51
Liabilities subject to compromise (Note 9)	32,540		32,581
Other noncurrent liabilities and deferred credits	1,671		1,702
Total liabilities	36,116		36,742
Total membership interests	(22,372)		(19,371)
Total liabilities and membership interests	13,744		17,371
Non-guarantors [Member]
Current assets:
Cash and cash equivalents	11		1	1	5
Current Assets	0		0
Advances to parent and affiliates	0		0
Trade accounts receivable – net	0		0
Income taxes receivable	0		0
Inventories	0		0
Commodity and other derivative contractual assets	0		0
Other current assets	0		0
Total current assets	11		1
Noncurrent Assets	0		0
Investments	5		8
Property, plant and equipment – net	3		3
Advances to parent and affiliates	0		0
Goodwill	0		0
Identifiable intangible assets – net	0		0
Commodity and other derivative contractual assets	0		0
Accumulated deferred income taxes	14		15
Other noncurrent assets	0		0
Total assets	33		27
Current liabilities:
Advances from Parent			0
Borrowings under debtor-in-possession credit facility (Note 8)	0
Long-term debt due currently	0		0
Trade accounts payable	0		0
Trade accounts and other payables to affiliates	0		2
Commodity and other derivative contractual liabilities	0		0
Margin deposits related to commodity positions	0		0
Accumulated deferred income taxes	0		0
Accrued income taxes payable to parent	2		0
Accrued taxes other than income	0		0
Accrued interest	0		0
Other current liabilities	0		0
Total current liabilities	2		2
Accumulated deferred income taxes	0		0
Commodity and other derivative contractual liabilities	0		0
Notes or other liabilities due affiliates	2
Borrowings under debtor-in-possession credit facility (Note 8)			0
Long-term debt, less amounts due currently (Note 8)	0		0
Liabilities subject to compromise (Note 9)	0		0
Other noncurrent liabilities and deferred credits	0		0
Total liabilities	4		2
Total membership interests	29		25
Total liabilities and membership interests	33		27
Eliminations [Member]
Current assets:
Cash and cash equivalents	0		0	$ 0	$ 0
Current Assets	0		0
Advances to parent and affiliates	0		(1,179)
Trade accounts receivable – net	0		0
Income taxes receivable	(488)		(176)
Inventories	0		0
Commodity and other derivative contractual assets	0		0
Other current assets	0		0
Total current assets	(488)		(1,355)
Noncurrent Assets	0		0
Investments	23,352		17,244
Property, plant and equipment – net	0		0
Advances to parent and affiliates	0		0
Goodwill	0		0
Identifiable intangible assets – net	0		0
Commodity and other derivative contractual assets	0		0
Accumulated deferred income taxes	(845)		(772)
Other noncurrent assets	0		0
Total assets	22,019		15,117
Current liabilities:
Advances from Parent			(1,179)
Borrowings under debtor-in-possession credit facility (Note 8)	0
Long-term debt due currently	0		0
Trade accounts payable	0		0
Trade accounts and other payables to affiliates	0		0
Commodity and other derivative contractual liabilities	0		0
Margin deposits related to commodity positions	0		0
Accumulated deferred income taxes	0		0
Accrued income taxes payable to parent	(488)		(176)
Accrued taxes other than income	0		0
Accrued interest	0		0
Other current liabilities	0		0
Total current liabilities	(488)		(1,355)
Accumulated deferred income taxes	(8)		38
Commodity and other derivative contractual liabilities	0		0
Notes or other liabilities due affiliates	(2)
Borrowings under debtor-in-possession credit facility (Note 8)			0
Long-term debt, less amounts due currently (Note 8)	0		0
Liabilities subject to compromise (Note 9)	(40,931)		(40,931)
Other noncurrent liabilities and deferred credits	0		0
Total liabilities	(41,429)		(42,248)
Total membership interests	63,448		57,365
Total liabilities and membership interests	$ 22,019		$ 15,117

[1] Net of accumulated impairment charges totaling $17.37 billion.