Income Tax (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income tax expense benefit continuing operations income tax reconciliation
Tax provision at U.S. statutory rate	$ 505	$ 3,215	$ 1,306
Tax effect of:
Tax-exempt investment income	(256)	(246)	(242)
State and local income tax	(3)	(4)	9
Prior year tax	23	(4)	59
Tax credits	(178)	(138)	(82)
Foreign tax rate differential	(45)	(41)	37
Goodwill impairment	408	0	0
Deferred tax benefit of converting Japan branch to subsidiary	(324)	0	0
Change in valuation allowance	15	16	7
Other, net	(17)	(5)	16
Provision for income tax expense (benefit)	$ 128	$ 2,793	$ 1,110

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to total foreign income tax expense or benefit. The foreign income tax expense or benefit difference represents the income tax expense or benefit at applicable domestic statutory income tax rates applied to foreign earnings or loss for the period versus the foreign income tax expense or benefit calculated by applying the appropriate foreign tax rates.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to nondeductible impairment losses under enacted tax laws.

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The sum of the differences between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to tax credits.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to income that is exempt from income taxes under enacted tax laws.

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