Investments (Details 5) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Other-than-temporary impairments on investments
Net impairment losses recognized in earnings	$ 0	$ 0	$ 0	$ (6)
Realized gains (losses) on investments
Net realized investment gains (losses)	(422)	205	(234)	117
Indemnity
Other-than-temporary impairments on investments
Total	0	0	0	(1)
Portion recognized in other comprehensive income	0	0	0	0
Net impairment losses recognized in earnings	0	0	0	(1)
Realized gains (losses) on investments
Net realized investment gains (losses)	(6)	5	1	7
Indemnity \| Fixed maturities
Available-for-sale securities:
Gross realized gains	0	2	2	5
Gross realized losses	0	(1)	0	(1)
Net realized gains	0	1	2	4
Other-than-temporary impairments on investments
Total	0	0	0	(1)
Indemnity \| Common stock
Trading securities:
Gross realized gains	0	4	2	5
Gross realized losses	0	(1)	0	(1)
Valuation adjustments	(6)	0	(6)	(2)
Net realized gains (losses)	(6)	3	(4)	2
Indemnity \| Equity securities
Available-for-sale securities:
Gross realized gains	0	0	3	1
Gross realized losses	0	1	0	0
Net realized gains	0	1	3	1
Other-than-temporary impairments on investments
Total	0	0	0	0
Exchange
Other-than-temporary impairments on investments
Total	0	0	0	(5)
Portion recognized in other comprehensive income	0	0	0	0
Net impairment losses recognized in earnings	0	0	0	(5)
Realized gains (losses) on investments
Net realized investment gains (losses)	(416)	200	(235)	110
Exchange \| Fixed maturities
Available-for-sale securities:
Gross realized gains	15	10	66	38
Gross realized losses	(5)	(4)	(22)	(16)
Net realized gains	10	6	44	22
Other-than-temporary impairments on investments
Total	0	0	0	(4)
Exchange \| Common stock
Trading securities:
Gross realized gains	56	24	183	113
Gross realized losses	(35)	(20)	(59)	(50)
Valuation adjustments	(450)	187	(421)	16
Net realized gains (losses)	(429)	191	(297)	79
Exchange \| Equity securities
Available-for-sale securities:
Gross realized gains	3	4	19	11
Gross realized losses	0	(1)	(1)	(2)
Net realized gains	3	3	18	9
Other-than-temporary impairments on investments
Total	$ 0	$ 0	$ 0	$ (1)

This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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