Realized Investment Gains and Losses and Change in Unrealized Investment Gains and Losses and Other Items (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Realized investment gains and losses summary:
Securities with embedded derivatives	$ 4	$ 4
Other	(1)
Total	13	12
Change in unrealized gains and losses summary:
Available for sale	241	142
Adjustment to deferred acquisition costs and life policy reserves	(7)
Pension obligations	2	1
Other	(5)	1
Income taxes on above	(79)	(46)
Total	146	86
Debt Securities
Realized investment gains and losses summary:
Gross realized gains	3	3
Gross realized losses
Change in unrealized gains and losses summary:
Available for sale	49	8
Equity Securities
Realized investment gains and losses summary:
Gross realized gains	23	35
Gross realized losses
Other-than-temporary impairments	(16)	(30)
Change in unrealized gains and losses summary:
Available for sale	179	122
Other Investments
Change in unrealized gains and losses summary:
Other	$ 2	$ 1

Other Comprehensive Income, Unrealized gains losses on deferred acquisition costs , Period Increase (Decrease)

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Net Increase or Decrease in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period.

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Tax effect of the change in accumulated other comprehensive income (loss), that is, the tax effect on items included in other comprehensive income (loss) during the period.

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The pretax amount of the change in the additional minimum pension liability not yet recognized pursuant to FAS 87 as a net periodic pension cost. If the additional pension liability required to be recognized exceeds the unrecognized prior service costs, then the excess (which is the net loss not yet recognized as net periodic pension cost) is to be recorded as a separate component in other comprehensive income, before adjusting for tax effects. In a subsequent measurement, the elimination or adjustment to the amount of the minimum pension liability recorded in accumulated other comprehensive income is included in this line. Eliminated upon adoption of FAS 158.

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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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