Available-for-sale securities (Details 2) (USD $) In Millions	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Less than 12 months
Fair Value	$ 99	$ 74	$ 454
Unrealized Losses	1	1	70
12 months or more
Fair Value	75	206	181
Unrealized Losses	11	38	66
Total
Fair Value	174	280	635
Unrealized Losses	12	39	136
Pretax charges recognized for "other-than-temporary" declines in the market values of equities securities	3	12	37
U.S. treasury bonds
Less than 12 months
Fair Value		4
Total
Fair Value		4
Other U.S. and non-U.S. government bonds
Less than 12 months
Fair Value	13	14
12 months or more
Fair Value	3	2	8
Unrealized Losses			1
Total
Fair Value	16	16	8
Unrealized Losses			1
Corporate bonds
Less than 12 months
Fair Value	29	25	176
Unrealized Losses			18
12 months or more
Fair Value	1	10	33
Unrealized Losses		1	5
Total
Fair Value	30	35	209
Unrealized Losses		1	23
Asset-backed securities
Less than 12 months
Fair Value	19	4	101
Unrealized Losses		1	16
12 months or more
Fair Value	19	44	30
Unrealized Losses	4	10	11
Total
Fair Value	38	48	131
Unrealized Losses	4	11	27
U.S. governmental agency mortgage-backed securities
Less than 12 months
Fair Value	16		7
12 months or more
Fair Value		3	19
Unrealized Losses			1
Total
Fair Value	16	3	26
Unrealized Losses			1
Residential mortgage-backed securities
Less than 12 months
Fair Value	2		32
Unrealized Losses			6
12 months or more
Fair Value	25	49	27
Unrealized Losses	4	10	14
Total
Fair Value	27	49	59
Unrealized Losses	4	10	20
Commercial mortgage-backed securities
Less than 12 months
Fair Value	3	24	71
Unrealized Losses			15
12 months or more
Fair Value	14	73	59
Unrealized Losses	1	14	32
Total
Fair Value	17	97	130
Unrealized Losses	1	14	47
Large capitalization value
Less than 12 months
Fair Value	14	2	60
Unrealized Losses	1		13
12 months or more
Fair Value	12	23	5
Unrealized Losses	2	3	2
Total
Fair Value	26	25	65
Unrealized Losses	3	3	15
Smaller company growth
Less than 12 months
Fair Value	3	1	7
Unrealized Losses			2
12 months or more
Fair Value	1	2
Total
Fair Value	4	3	7
Unrealized Losses			$ 2

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- Definition

The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ Details

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This item represents the excess of [amortized] cost over fair value of securities that have been in a loss position for twelve months or longer for those securities which are categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 03-1
-Paragraph 21
-Subparagraph a(2)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 17
-Subparagraph a(1)

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This item represents the excess of [amortized] cost over fair value of securities in a loss position and which are categorized neither as held-to-maturity nor trading securities.

+ References

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This item represents the fair value of securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

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This item represents the excess of [amortized] cost over fair value of securities that have been in a loss position for less than twelve months for those securities which are categorized neither as held-to-maturity nor trading securities.

+ References

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This item represents the fair value of securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

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This item represents the fair value of securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer.

+ References

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