Consolidated Statements Of Shareholders' Equity (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements Of Shareholders' Equity [Abstract]
Net unrealized appreciation on investments, Change in period, income tax (expense) benefit	$ (49)	$ 14
Cumulative translation adjustment, Change in period, income tax (expense) benefit	(32)	(64)
Pension liability adjustment, Change in period, income tax benefit (expense)	$ 1	$ 2

Tax effect of the gross appreciation or the gross loss, net of reclassification adjustment, in the value of the total unsold available-for-sale securities at the end of an accounting period.

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Tax effects of the increase (decrease) to accumulated comprehensive income during the period related to benefit plans. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label.

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- Definition

Tax effect of the adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label.

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