Segments of Operations - Earnings before income taxes by segment and sub-segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	$ 299	$ 241	$ 675	$ 499
Realized gains (losses) on securities	(93)	43	(108)	120
Earnings from continuing operations before income taxes	206	288	567	623
Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	196	152	403	286
Investment and other income, net	149	136	364	290
Earnings before realized gains (losses) and income taxes	345	288	767	576
Other
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	(46)	(69)	(92)	(128)
Other \| Continuing operations \| Real estate-related entities
Segment Reporting Information [Line Items]
Earnings from real-estate related investments, net of DAC	0	22	0	51
Property and transportation \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	39	62	101	118
Specialty casualty \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	130	71	254	127
Specialty financial \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	37	21	66	46
Other specialty \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	(9)	(1)	(16)	(4)
Other lines \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	$ (1)	$ (1)	$ (2)	$ (1)

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Net investment income plus other income less other expenses.

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Underwriting income (loss) for the property and casualty insurance segment, which is calculated as premiums earned less losses and loss adjustment expenses less commissions and other underwriting expenses.

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Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

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