Policyholders' account balances (Policyholder Account Balance Rollforward) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Policyholder Account Balance [Line Items]
Balance – beginning of period		$ 6,868	$ 6,574	$ 6,789	$ 2,573
Policyholder Account Balance, Premium Received		818	418
Policyholder Account Balance, Policy Charge	[1]	(105)	(104)
Policyholder Account Balance, Surrender and Withdrawal		(327)	(183)
Policyholder Account Balance, Benefit Payment	[2]	(215)	(87)
Policyholder Account Balance, Interest Expense		108	68
Policyholder Account Balance, Increase (Decrease) from Other Change		(200)	(125)
Balance - end of period		6,868	6,574	6,789	2,573
Balance – beginning of period		712	604	673	567
Policyholder Account Balance, Other Reconciling Items		556
Policyholder Account Balance, Ending Balance		8,136	7,178
Huatai Group
Policyholder Account Balance [Line Items]
Policyholder Account Balance, Acqusition			4,014
Universal Life
Policyholder Account Balance [Line Items]
Balance – beginning of period		1,869	1,785	1,876	1,199
Policyholder Account Balance, Premium Received		204	174
Policyholder Account Balance, Policy Charge	[1]	(98)	(96)
Policyholder Account Balance, Surrender and Withdrawal		(95)	(62)
Policyholder Account Balance, Benefit Payment	[2]	(59)	(6)
Policyholder Account Balance, Interest Expense		38	30
Policyholder Account Balance, Increase (Decrease) from Other Change		3	(56)
Balance - end of period		1,869	1,785	1,876	1,199
Policyholder Account Balance, Ending Balance		$ 1,869	$ 1,785
Policyholder Account Balance, Weighted Average Crediting Rate		2.70%	3.10%
Policyholder Account Balance, Net Amount at Risk	[3]	$ 12,648	$ 11,705
Policyholder Account Balance, Cash Surrender Value		1,699	1,573
Universal Life | Huatai Group
Policyholder Account Balance [Line Items]
Policyholder Account Balance, Acqusition			602
Annuities [Member]
Policyholder Account Balance [Line Items]
Balance – beginning of period	[4]	2,608	2,340	2,411	0
Policyholder Account Balance, Premium Received	[4]	294	79
Policyholder Account Balance, Policy Charge	[1],[4]	0	0
Policyholder Account Balance, Surrender and Withdrawal	[4]	(30)	(8)
Policyholder Account Balance, Benefit Payment	[2],[4]	(116)	(38)
Policyholder Account Balance, Interest Expense	[4]	29	16
Policyholder Account Balance, Increase (Decrease) from Other Change	[4]	20	(34)
Balance - end of period	[4]	2,608	2,340	2,411	0
Policyholder Account Balance, Ending Balance		$ 2,608	$ 2,340
Policyholder Account Balance, Weighted Average Crediting Rate		1.60%	2.70%
Policyholder Account Balance, Net Amount at Risk	[3]	$ 0	$ 0
Policyholder Account Balance, Cash Surrender Value		1,691	1,474
Annuities [Member] | Huatai Group
Policyholder Account Balance [Line Items]
Policyholder Account Balance, Acqusition	[4]		2,325
Insurance, Other
Policyholder Account Balance [Line Items]
Balance – beginning of period	[5]	2,391	2,449	2,502	1,374
Policyholder Account Balance, Premium Received	[5]	320	165
Policyholder Account Balance, Policy Charge	[1],[5]	(7)	(8)
Policyholder Account Balance, Surrender and Withdrawal	[5]	(202)	(113)
Policyholder Account Balance, Benefit Payment	[2],[5]	(40)	(43)
Policyholder Account Balance, Interest Expense	[5]	41	22
Policyholder Account Balance, Increase (Decrease) from Other Change	[5]	(223)	(35)
Balance - end of period	[5]	2,391	2,449	$ 2,502	$ 1,374
Policyholder Account Balance, Ending Balance		$ 2,391	$ 2,449
Policyholder Account Balance, Weighted Average Crediting Rate		2.70%	1.20%
Policyholder Account Balance, Net Amount at Risk	[3]	$ 440	$ 576
Policyholder Account Balance, Cash Surrender Value		$ 2,091	2,173
Insurance, Other | Huatai Group
Policyholder Account Balance [Line Items]
Policyholder Account Balance, Acqusition	[5]		$ 1,087

[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.