Fair Value Disclosure (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Available for sale securities
Auction rate securities settlements reclassified to net income	$ 3
Auction rate securities marked to market	2	(4)
Auction rate securities
Available for sale securities
Gains on disposition of securities	14
Auction rate securities settlements reclassified to net income	3
Auction rate securities marked to market	2
Auction rate securities \| Sale Increment One
Available for sale securities
Auction rate securities sold	17
Auction rate securities \| Sale Increment Two
Available for sale securities
Auction rate securities sold	39
Auction rate securities \| Sale Increment Three
Available for sale securities
Auction rate securities sold	$ 19

Net of tax amount of the appreciation (loss) in value of unsold available-for-sale securities attributable to the parent entity. Excludes amounts related to other than temporary impairment (OTTI) losses.

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+ Details

- Definition

Net of tax amount of the income statement impact of the reclassification adjustment for unrealized gain (loss) realized upon the sale of available-for-sale securities.

+ References

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+ Details