Income Taxes (Components of deferred tax assets and liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Components of Deferred Tax Assets [Abstract]
Reserves and allowances, current	$ 66	$ 54
Intangibles, current	1	0
Debt cancellation and other, current	0	0
Net operating loss and credit carryforwards, current	181	206
Deferred tax assets - current	248	260
Reserves and allowances, noncurrent	41	59
Intangibles, noncurrent	0	0
Debt cancellation and other, noncurrent	58	41
Net operating loss and credit carryforwards, noncurrent	56	69
Deferred tax assets - non-current	155	169
Reserves and allowances	107	113
Intangibles	1	0
Debt cancellation and other	58	41
Net operating loss and credit carryforwards	237	275
Total deferred tax assets	403	429
Components of Deferred Tax Liabilities [Abstract]
Property and equipment, current	0	0
Intangibles, current	0	0
Valuation allowance - current	0	0
Total deferred tax liability, current	0	0
Property and equipment, noncurrent	(1,535)	(1,259)
Intangibles, noncurrent	(312)	(369)
Valuation allowance - non-current	0	0
Total deferred tax liability, noncurrent	(1,847)	(1,628)
Property and equipment	(1,535)	(1,259)
Intangibles	(312)	(369)
Valuation allowance	0	0
Total deferred tax liability	(1,847)	(1,628)
Net deferred tax asset (liability) - current	248	260
Net deferred tax assets (liability) - non-current	(1,692)	(1,459)
Total deferred income tax asset (liability)	$ (1,444)	$ (1,199)