Segments of Operations - Earnings before income taxes by segment and sub-segment (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	$ 376	$ 258
Realized gains (losses) on securities	(15)	77
Earnings from continuing operations before income taxes	361	335
Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	207	134
Investment and other income, net	215	154
Earnings before realized gains (losses) and income taxes	422	288
Other
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	(46)	(59)
Other \| Continuing operations \| Real estate-related entities
Segment Reporting Information [Line Items]
Earnings from real-estate related investments, net of DAC	0	29
Property and transportation \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	62	56
Specialty casualty \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	124	56
Specialty financial \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	29	25
Other specialty \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	(7)	(3)
Other lines \| Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	$ (1)	$ 0

Earnings from real-estate related investments, net of DAC

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Net investment income plus other income less other expenses.

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The net result for the period of deducting operating expenses from operating revenues (excluding realized gains (losses) on securities and subsidiaries) before income taxes.

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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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The net result for the period of deducting operating expenses from operating revenues.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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