Fair Value Measurements (Details 3) (Debt Securities, USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Amortized cost basis, unrealized gains and losses, and approximate fair values of investments in held-to-maturity securities
Cost Basis	$ 414	$ 476
Unrealized Gains	45	91
Unrealized Losses	0	0
Fair Value	459	567
OE
Amortized cost basis, unrealized gains and losses, and approximate fair values of investments in held-to-maturity securities
Cost Basis	178	190
Unrealized Gains	17	51
Unrealized Losses	0	0
Fair Value	195	241
CEI
Amortized cost basis, unrealized gains and losses, and approximate fair values of investments in held-to-maturity securities
Cost Basis	287	340
Unrealized Gains	27	41
Unrealized Losses	0	0
Fair Value	$ 314	$ 381

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

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+ Details