Restricted Cash, Cash Equivalents and Investments (Details 1) (USD $) In Millions	6 Months Ended	12 Months Ended
Jun. 30, 2011	Dec. 31, 2010
Restricted investments classified as available-for-sale:
Available-for-sale, Debt securities, Fair Value	$ 241	$ 254
Corporate Securities [Member] \| Restricted Investments [Member]
Restricted investments classified as available-for-sale:
Available-for-sale Securities, Debt Maturities, Amortized Cost, Total	57	71
Available-for-sale, Debt securities, Fair Value	58	71
Available-for-sale, Debt securities, Unrealized Gains	1	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale, Debt securities, Weighted-average remaining maturity	29 months	30 months
Agency Securities [Member] \| Restricted Investments [Member]
Restricted investments classified as available-for-sale:
Available-for-sale Securities, Debt Maturities, Amortized Cost, Total	111	106
Available-for-sale, Debt securities, Fair Value	112	107
Available-for-sale, Debt securities, Unrealized Gains	1	1
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale, Debt securities, Weighted-average remaining maturity	22 months	26 months
Government Securities [Member] \| Restricted Investments [Member]
Restricted investments classified as available-for-sale:
Available-for-sale Securities, Debt Maturities, Amortized Cost, Total	71	76
Available-for-sale, Debt securities, Fair Value	71	76
Available-for-sale, Debt securities, Unrealized Gains	0	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale, Debt securities, Weighted-average remaining maturity	25 months	28 months
Restricted Investments [Member]
Restricted investments classified as available-for-sale:
Available-for-sale Securities, Debt Maturities, Amortized Cost, Total	239	253
Available-for-sale, Debt securities, Fair Value	241	254
Available-for-sale, Debt securities, Unrealized Gains	2	1
Available-for-sale Securities, Gross Unrealized Losses	$ 0	$ 0
Available-for-sale, Debt securities, Weighted-average remaining maturity	25 months	27 months

This item represents the total of all debt securities grouped by maturity dates, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are classified neither as held-to-maturity nor trading securities.

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This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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- Definition

Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale that are pledged to one or more secured parties who have the right to buy, sell, or re-pledge the collateral.

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