Income Taxes (Components of deferred tax assets and liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Components Of Deferred Tax Assets And Liabilities [Line Items]
Reserves and allowances	$ 113	$ 119
Intangibles	0	0
Debt cancellation and other	41	37
Net operating loss and credit carryforwards	275	449
Deferred tax assets - current	260	265
Deferred tax assets - non-current	169	340
Total deferred tax assets	429	605
Property and equipment	(1,259)	(1,236)
Intangibles	(369)	(405)
Valuation allowance - current	0	0
Valuation allowance - non-current	0	(1)
Valuation allowance	0	(1)
Deferred tax liability - current	0	0
Deferred tax liability - non-current	(1,628)	(1,642)
Total deferred tax liability	(1,628)	(1,642)
Net deferred tax asset (liability) - current	260	265
Net deferred tax assets (liability) - non-current	(1,459)	(1,302)
Total deferred income tax asset (liability)	(1,199)	(1,037)
Current [Member]
Components Of Deferred Tax Assets And Liabilities [Line Items]
Reserves and allowances	54	61
Intangibles	0	0
Debt cancellation and other	0	0
Net operating loss and credit carryforwards	206	204
Property and equipment	0	0
Intangibles	0	0
Non-Current [Member]
Components Of Deferred Tax Assets And Liabilities [Line Items]
Reserves and allowances	59	58
Intangibles	0	0
Debt cancellation and other	41	37
Net operating loss and credit carryforwards	69	245
Property and equipment	(1,259)	(1,236)
Intangibles	$ (369)	$ (405)