Condensed Combined Debtors' Financial Information (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	Dec. 31, 2012	Dec. 31, 2011
Income Statement:
Operating revenues	$ 385	$ 340	$ 1,007	$ 1,007
Operating expenses	(816)	(411)	(1,548)	(1,224)
Reorganization items, net	(24)	(7)	(99)	(9)
Provision (benefit) for income taxes	(3)	47	25	204
Income (Loss) from discontinued operations, net of tax	(1)	(76)	16	(129)
Net Income (loss)	(448)	(162)	(614)	(348)
Other comprehensive income (loss), net of tax	0	(13)	29	(34)
Comprehensive Income (loss)	(455)	(180)	(606)	(394)
Assets:
Total current assets	1,525		1,525		1,323
Investments in unconsolidated affiliates	543		543		534
Property, Plant and Equipment, less accumulated depreciation	3,934		3,934		4,516
Total other assets	94		94		128
Total Assets	7,054		7,054		7,520
Property, Plant and Equipment, accumulated depreciation (in dollars)	1,275		1,275		1,431
Liabilities and Shareholders' Equity:
Total current liabilities	238		238		820
Liabilities subject to compromise	3,979		3,979		3,959
Deferred taxes	53		53		81
Other long-term liabilities	510		510		528
Total Liabilities	6,795		6,795		6,788
Total equity	259	1,482	259	1,482	732	1,664
Total Liabilities and Equity	7,054		7,054		7,520
Net Cash provided by (used in):
Operating cash flows from continuing operations			171	(535)
Operating cash flows from discontinued operations, net			(2)	(5)
Net cash provided by (used in) operating activities			169	(540)
Net cash provided by (used in) financing activities			151	354
Net cash provided by (used in) investing activities			(72)	(361)
Net increase (decrease) in cash and cash equivalents			250	(523)
Cash and cash equivalents at beginning of period from continuing operations			888	1,221
Cash and cash equivalents at end of period from continuing operations	1,138	698	1,138	698
Net increase (decrease) in cash and cash equivalents from discontinued operations			(2)	(24)
Cash and cash equivalents at beginning of period from discontinued operations			2	79
Cash and cash equivalents at end of period from discontinued operations	0	55	0	55
Debtor Entities
Income Statement:
Operating revenues	234		620
Operating expenses	(719)		(1,256)
Other Income	26		45
Reorganization items, net	(24)		(99)
Provision (benefit) for income taxes	(4)		(110)
Income (Loss) from discontinued operations, net of tax	0		19
Net income (loss) attributable to Debtor Entities	(487)		(781)
Equity in income of non-Debtor Entities, net of tax	32		146
Net Income (loss)	(455)		(635)
Comprehensive Income (loss)	(455)		(606)
Assets:
Total current assets	836		836		638
Investments in unconsolidated affiliates	171		171		152
Property, Plant and Equipment, less accumulated depreciation	911		911		1,428
Investment in non-debtor entities	2,057		2,057		2,019
Total other assets	886		886		974
Total Assets	4,861		4,861		5,211
Property, Plant and Equipment, accumulated depreciation (in dollars)	894		894		845
Liabilities and Shareholders' Equity:
Total current liabilities	240		240		94
Liabilities subject to compromise	3,979		3,979		3,959
Deferred taxes	123		123		131
Other long-term liabilities	259		259		295
Total Liabilities	4,601		4,601		4,479
Total equity	260		260		732
Total Liabilities and Equity	4,861		4,861		5,211
Net Cash provided by (used in):
Operating cash flows from continuing operations			20
Operating cash flows from discontinued operations, net			(2)
Net cash provided by (used in) operating activities			18
Net cash provided by (used in) financing activities			218
Net cash provided by (used in) investing activities			14
Net increase (decrease) in cash and cash equivalents			252
Cash and cash equivalents at beginning of period from continuing operations			425
Cash and cash equivalents at end of period from continuing operations	677		677
Net increase (decrease) in cash and cash equivalents from discontinued operations			(2)
Cash and cash equivalents at beginning of period from discontinued operations			2
Cash and cash equivalents at end of period from discontinued operations	0		0
Cash paid for reorganization items, net			$ 54