Condensed Combined Debtors' Financial Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Income Statement:
Operating revenues	$ 315	$ 324	$ 622	$ 667
Operating expenses	(378)	(424)	(732)	(815)
Reorganization items	(47)	0	(75)	0
Benefit for income taxes	25	81	28	157
Income (Loss) from discontinued operations, net of tax	18	(29)	17	(53)
Net Loss	(84)	(104)	(166)	(186)
Other comprehensive loss, net of tax	31	(37)	29	(21)
Comprehensive Loss	(60)	(146)	(151)	(214)
Assets:
Total current assets	1,467		1,467		1,323
Investments in unconsolidated affiliates	522		522		534
Property, Plant and Equipment, less accumulated depreciation	4,465		4,465		4,516
Total other assets	96		96		128
Total Assets	7,525		7,525		7,520
Property, Plant and Equipment, accumulated depreciation (in dollars)	1,566		1,566		1,431
Liabilities and Shareholders' Equity:
Total current liabilities	287		287		820
Liabilities subject to compromise	3,981		3,981		3,959
Deferred taxes	82		82		81
Other long-term liabilities	505		505		528
Total Liabilities	6,846		6,846		6,788
Total equity	679	1,662	679	1,662	732	1,664
Total Liabilities and Equity	7,525		7,525		7,520
Net Cash provided by (used in):
Operating cash flows from continuing operations			85	(340)
Operating cash flows from discontinued operations, net			(2)	(14)
Operating cash flows from continuing operations			83	(354)
Net cash provided by financing activities			162	300
Net cash provided by investing activities			(79)	(237)
Net increase in cash and cash equivalents			168	(264)
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	1,056	957	1,056	957
Net increase in cash and cash equivalents from discontinued operations			(2)	(27)
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	52	0	52
Debtor Entities
Income Statement:
Operating revenues	205		386
Operating expenses	(273)		(537)
Other income	7		19
Reorganization items	(47)		(75)
Benefit for income taxes	(9)		(106)
Income (Loss) from discontinued operations, net of tax	19		19
Net loss attributable to Debtor Entities	(98)		(294)
Equity in income of non-Debtor Entities, net of tax	7		114
Net Loss	(91)		(180)
Comprehensive Loss	(60)		(151)
Assets:
Total current assets	823		823		638
Investments in unconsolidated affiliates	153		153		152
Property, Plant and Equipment, less accumulated depreciation	1,397		1,397		1,428
Investment in non-debtor entities	2,046		2,046		2,019
Total other assets	911		911		974
Total Assets	5,330		5,330		5,211
Property, Plant and Equipment, accumulated depreciation (in dollars)	894		894		845
Liabilities and Shareholders' Equity:
Total current liabilities	264		264		94
Liabilities subject to compromise	3,981		3,981		3,959
Deferred taxes	150		150		131
Other long-term liabilities	256		256		295
Total Liabilities	4,651		4,651		4,479
Total equity	679		679		732
Total Liabilities and Equity	5,330		5,330		5,211
Net Cash provided by (used in):
Operating cash flows from continuing operations			8
Operating cash flows from discontinued operations, net			(2)
Operating cash flows from continuing operations			6
Net cash provided by financing activities			197
Net cash provided by investing activities			3
Net increase in cash and cash equivalents			208
Cash and cash equivalents at beginning of period from continuing operations			425
Cash and cash equivalents at end of period from continuing operations	633		633
Net increase 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			$ 27