Income Taxes Level 4 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Income Tax Disclosure [Line Items]
Tax Benefit from American Taxpayer Relief Act of 2012	$ 29

Tax Benefit from American Taxpayer Relief Act of 2012

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration