Separate accounts (Separate account liabilities rollforward) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023
Separate Account, Liability [Line Items]
Separate Account, Liability, Beginning Balance		$ 5,573	$ 5,190
Separate Account, Liability, Premium and Deposit		1,629	995
Separate Account, Liability, Policy Charge		(158)	(138)
Separate Account, Liability, Surrender and Withdrawal		(910)	(601)
Separate Account, Liability, Benefit Payment		(430)	(381)
Separate Account, Liability, Increase (Decrease) from Invested Performance		630	611
Separate Account, Liability, Increase (Decrease) from Other Change		(103)	(103)
Separate Account, Liability, Ending Balance		6,231	5,573
Separate Account, Liability, Cash Surrender Value, Amount	[1]	$ 5,853	$ 5,398

[1] Cash surrender value represents the amount of the contract holder's account balances distributable at the balance sheet date less certain surrender charges