Consolidated Balance Sheets (Parentheticals) (Unaudited) $ in Millions	Sep. 30, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares
Statement of Financial Position [Abstract]
Debt Securities, Available for sale, Allowance for Credit Loss	$ 147	$ 14
Available for sale, at amortized cost	93,316	90,493
Debt Securities, Held to maturity, Allowance for Credit Loss	33	35
Held to maturity, Fair Value	8,491	10,647
Short-term investments amortized cost	4,536	3,147
Premium Receivable, Allowance for Credit Loss	51	46
Reinsurance Recoverable, Allowance for Credit Loss	$ 352	$ 329
Common Shares, shares issued \| shares	446,376,614	474,021,114
Common Shares, shares outstanding \| shares	415,020,484	426,572,612
Common Shares in treasury, shares \| shares	31,356,130	47,448,502

Amount of short-term investments at amortized cost

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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The carrying value as of the balance sheet date of the estimated valuation allowance to reduce gross premiums receivable to net realizable value.

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Amount of allowance for credit loss on reinsurance recoverable.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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