Separate accounts (Separate account liabilities rollforward) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023
Separate Account, Liability [Line Items]
Separate Account, Liability, Beginning Balance		$ 5,573	$ 5,190
Separate Account, Liability, Premium and Deposit		576	517
Separate Account, Liability, Policy Charge		(80)	(70)
Separate Account, Liability, Surrender and Withdrawal		(426)	(246)
Separate Account, Liability, Benefit Payment		(208)	(193)
Separate Account, Liability, Increase (Decrease) from Invested Performance		502	361
Separate Account, Liability, Increase (Decrease) from Other Change		(103)	15
Separate Account, Liability, Ending Balance		5,834	5,574
Separate Account, Liability, Cash Surrender Value, Amount	[1]	$ 5,625	$ 5,369

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