Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	$ 38,728	$ 37,627
Debt securities, trading	198	70
Debt securities	38,926	37,697
Equity securities	1,051	1,139
Short term and other	4,316	4,706
Receivables	20	19
Payable to brokers	(54)	(82)
Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	23,394	22,117
States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	7,810	8,317
Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	7,524	7,193
Level 1
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	137	120
Debt securities, trading	198	1
Debt securities	335	121
Equity securities	603	669
Short term and other	4,274	4,539
Receivables
Payable to brokers	(54)	(82)
Level 1 \| Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	137	120
Level 1 \| States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities
Level 1 \| Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities
Level 2
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	36,694	35,866
Debt securities, trading		69
Debt securities	36,694	35,935
Equity securities	422	435
Short term and other	42	167
Receivables	20	19
Payable to brokers
Level 2 \| Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	22,286	21,187
Level 2 \| States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	7,767	8,274
Level 2 \| Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	6,641	6,405
Level 3
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	1,897	1,641
Debt securities, trading
Debt securities	1,897	1,641
Equity securities	26	35
Short term and other
Receivables
Payable to brokers
Level 3 \| Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	971	810
Level 3 \| States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	43	43
Level 3 \| Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	$ 883	$ 788

Broker-Dealer, Payable To Other Broker-Dealer, Fair Value Disclosure

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Short-Term Investments And Other, Fair Value Disclosure

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Amount 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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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Fair value portion of receivables, including, but not limited to, trade account receivables, note receivables, and loan receivables.

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