Policyholders' account balances (Policyholder Account Balance Rollforward) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Policyholder Account Balance [Line Items]
Balance – beginning of period		$ 6,612	$ 2,607	$ 6,789	$ 2,573
Policyholder Account Balance, Premium Received		564	170
Policyholder Account Balance, Policy Charge	[1]	(70)	(68)
Policyholder Account Balance, Surrender and Withdrawal		(238)	(77)
Policyholder Account Balance, Benefit Payment	[2]	(138)	(26)
Policyholder Account Balance, Interest Expense		82	29
Policyholder Account Balance, Increase (Decrease) from Other Change		(377)	6
Balance - end of period		6,612	2,607	6,789	2,573
Balance – beginning of period		675	608	673	567
Policyholder Account Balance, Other Reconciling Items		500
Policyholder Account Balance, Ending Balance		7,787	3,215
Universal Life
Policyholder Account Balance [Line Items]
Balance – beginning of period		1,778	1,219	1,876	1,199
Policyholder Account Balance, Premium Received		139	106
Policyholder Account Balance, Policy Charge	[1]	(65)	(63)
Policyholder Account Balance, Surrender and Withdrawal		(65)	(36)
Policyholder Account Balance, Benefit Payment	[2]	(56)	(4)
Policyholder Account Balance, Interest Expense		25	16
Policyholder Account Balance, Increase (Decrease) from Other Change		(76)	1
Balance - end of period		1,778	1,219	1,876	1,199
Policyholder Account Balance, Ending Balance		$ 1,778	$ 1,219
Policyholder Account Balance, Weighted Average Crediting Rate		2.80%	2.70%
Policyholder Account Balance, Net Amount at Risk	[3]	$ 11,987	$ 11,634
Policyholder Account Balance, Cash Surrender Value		1,611	1,013
Annuities [Member]
Policyholder Account Balance [Line Items]
Balance – beginning of period	[4]	2,521		2,411
Policyholder Account Balance, Premium Received	[4]	208
Policyholder Account Balance, Policy Charge	[1],[4]	0
Policyholder Account Balance, Surrender and Withdrawal	[4]	(20)
Policyholder Account Balance, Benefit Payment	[2],[4]	(81)
Policyholder Account Balance, Interest Expense	[4]	30
Policyholder Account Balance, Increase (Decrease) from Other Change	[4]	(27)
Balance - end of period	[4]	2,521		2,411
Policyholder Account Balance, Ending Balance		$ 2,521
Policyholder Account Balance, Weighted Average Crediting Rate		2.50%
Policyholder Account Balance, Net Amount at Risk	[3]	$ 0
Policyholder Account Balance, Cash Surrender Value		1,618
Insurance, Other
Policyholder Account Balance [Line Items]
Balance – beginning of period	[5]	2,313	1,388	2,502	1,374
Policyholder Account Balance, Premium Received	[5]	217	64
Policyholder Account Balance, Policy Charge	[1],[5]	(5)	(5)
Policyholder Account Balance, Surrender and Withdrawal	[5]	(153)	(41)
Policyholder Account Balance, Benefit Payment	[2],[5]	(1)	(22)
Policyholder Account Balance, Interest Expense	[5]	27	13
Policyholder Account Balance, Increase (Decrease) from Other Change	[5]	(274)	5
Balance - end of period	[5]	2,313	1,388	$ 2,502	$ 1,374
Policyholder Account Balance, Ending Balance		$ 2,313	$ 1,388
Policyholder Account Balance, Weighted Average Crediting Rate		2.90%	2.00%
Policyholder Account Balance, Net Amount at Risk	[3]	$ 454	$ 201
Policyholder Account Balance, Cash Surrender Value		$ 2,013	$ 1,316

[1] Contracts included in the policyholder account balances are generally charged a premium and/or monthly assessments on the basis of the account balance.

[2] Includes benefit payments upon maturity as well as death benefits.

[3] For those guarantees of benefits that are payable in the event of death, the net amount at risk is defined as the current guaranteed minimum death benefit in excess of the current account balance at the balance sheet date.

[4] Relates to Huatai Life.

[5] Primarily comprises policyholder account balances related to investment linked products including endowment and investment contracts, none of which bear significant insurance risk.