Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	$ 39,093	$ 37,627
Debt securities, trading	256	70
Debt securities	39,349	37,697
Equity securities	1,057	1,139
Short term and other	3,922	4,706
Receivables	17	19
Payable to brokers	(81)	(82)
Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	23,637	22,117
States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	8,001	8,317
Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	7,455	7,193
Level 1
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	135	120
Debt securities, trading	203	1
Debt securities	338	121
Equity securities	607	669
Short term and other	3,854	4,539
Receivables
Payable to brokers	(81)	(82)
Level 1 \| Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	135	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	37,143	35,866
Debt securities, trading	53	69
Debt securities	37,196	35,935
Equity securities	421	435
Short term and other	68	167
Receivables	17	19
Payable to brokers
Level 2 \| Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	22,590	21,187
Level 2 \| States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	7,957	8,274
Level 2 \| Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	6,596	6,405
Level 3
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	1,815	1,641
Debt securities, trading
Debt securities	1,815	1,641
Equity securities	29	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	912	810
Level 3 \| States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	44	43
Level 3 \| Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Debt securities	$ 859	$ 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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