Discontinued Operations Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Income (Loss)	$ 410	$ 312
Income Tax Expense (Benefit)	105	73
Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue	10
Disposal Group, Including Discontinued Operation, Operating Expense	5
Depreciation and Amortization, Discontinued Operations	5
Taxes Other than Income Related to Discontinued Operations	0
Assets (Gains) and Losses Related to Sale of Segment	0
Operating Income (Loss)	0
Other Nonoperating Income (Expense)	1
Income Tax Expense (Benefit)	(1)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ 0