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Investments - Schedule of sources of net investment income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Net Investment Income [Line Items]
Investment income	$ 770	$ 802	$ 758
Equity in earnings of partnerships and similar investments	56	46	99
Investment expenses	(25)	(22)	(16)
Net investment income	745	780	742
Net investment income
Net Investment Income [Line Items]
Change in fair value of equity securities	(14)	57	36
Fixed maturities | Net investment income
Net Investment Income [Line Items]
Change in fair value of fixed maturities	6	17	(3)
Fixed maturities | Net investment income
Net Investment Income [Line Items]
Investment income	569	544	502
Equity securities | Net investment income
Net Investment Income [Line Items]
Dividends	33	29	34
Cash and cash equivalents
Net Investment Income [Line Items]
Investment income	53	56	43
Mortgage loans
Net Investment Income [Line Items]
Investment income	44	32	24
Other
Net Investment Income [Line Items]
Investment income	$ 23	$ 21	$ 23

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