Separate accounts (Separate account liabilities rollforward) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2026	Mar. 31, 2025
Separate Account, Liability [Line Items]
Separate Account, Liability, Beginning Balance		$ 6,925	$ 6,231
Separate Account, Liability, Premium and Deposit		367	490
Separate Account, Liability, Policy Charge		(44)	(33)
Separate Account, Liability, Surrender and Withdrawal		(337)	(243)
Separate Account, Liability, Benefit Payment		(125)	(113)
Separate Account, Liability, Increase (Decrease) from Invested Performance		23	5
Separate Account, Liability, Increase (Decrease) from Other Change		(91)	(52)
Separate Account, Liability, Ending Balance		6,718	6,285
Separate Account, Liability, Cash Surrender Value, Amount	[1]	$ 6,239	$ 5,898

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