Separate accounts (Separate account liabilities rollforward) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023
Separate Account, Liability [Line Items]
Separate Account, Liability, Beginning Balance		$ 5,573	$ 5,190
Separate Account, Liability, Premium and Deposit		945	724
Separate Account, Liability, Policy Charge		(118)	(103)
Separate Account, Liability, Surrender and Withdrawal		(666)	(407)
Separate Account, Liability, Benefit Payment		(320)	(291)
Separate Account, Liability, Increase (Decrease) from Invested Performance		625	382
Separate Account, Liability, Increase (Decrease) from Other Change		(43)	(189)
Separate Account, Liability, Ending Balance		5,996	5,306
Separate Account, Liability, Cash Surrender Value, Amount	[1]	$ 5,790	$ 5,285

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