Policyholders' account balances (Policyholder Account Balance Rollforward) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Policyholder Account Balance [Line Items]
Balance – beginning of period		$ 6,748	$ 6,789
Policyholder Account Balance, Premium Received		248	334
Policyholder Account Balance, Policy Charge	[1]	(31)	(36)
Policyholder Account Balance, Surrender and Withdrawal		(89)	(119)
Policyholder Account Balance, Benefit Payment	[2]	(87)	(116)
Policyholder Account Balance, Interest Expense		38	43
Policyholder Account Balance, Increase (Decrease) from Other Change		17	(15)
Balance – end of period		6,844	6,880
Unearned Revenue Liability		719	680	$ 711	$ 673
Policyholder Account Balance, Other Reconciling Items	[3]	566
Policyholder Account Balance, Ending Balance		8,129	7,560
Universal Life
Policyholder Account Balance [Line Items]
Balance – beginning of period		1,809	1,876
Policyholder Account Balance, Premium Received		53	72
Policyholder Account Balance, Policy Charge	[1]	(29)	(34)
Policyholder Account Balance, Surrender and Withdrawal		(29)	(32)
Policyholder Account Balance, Benefit Payment	[2]	(17)	(54)
Policyholder Account Balance, Interest Expense		12	13
Policyholder Account Balance, Increase (Decrease) from Other Change		13	(1)
Balance – end of period		1,812	1,840
Policyholder Account Balance, Ending Balance		$ 1,812	$ 1,840
Policyholder Account Balance, Weighted Average Crediting Rate	[4]	2.70%	2.90%
Policyholder Account Balance, Net Amount at Risk	[5]	$ 12,079	$ 12,014
Policyholder Account Balance, Cash Surrender Value		1,659	1,623
Annuities [Member]
Policyholder Account Balance [Line Items]
Balance – beginning of period	[6]	2,585	2,411
Policyholder Account Balance, Premium Received	[6]	101	131
Policyholder Account Balance, Policy Charge	[1],[6]	0	0
Policyholder Account Balance, Surrender and Withdrawal	[6]	(9)	(10)
Policyholder Account Balance, Benefit Payment	[2],[6]	(48)	(59)
Policyholder Account Balance, Interest Expense	[6]	10	16
Policyholder Account Balance, Increase (Decrease) from Other Change	[6]	5	(5)
Balance – end of period	[6]	2,644	2,484
Policyholder Account Balance, Ending Balance		$ 2,644	$ 2,484
Policyholder Account Balance, Weighted Average Crediting Rate	[4]	1.60%	2.60%
Policyholder Account Balance, Net Amount at Risk	[5]	$ 0	$ 0
Policyholder Account Balance, Cash Surrender Value		1,728	1,605
Insurance, Other
Policyholder Account Balance [Line Items]
Balance – beginning of period	[7]	2,354	2,502
Policyholder Account Balance, Premium Received	[7]	94	131
Policyholder Account Balance, Policy Charge	[1],[7]	(2)	(2)
Policyholder Account Balance, Surrender and Withdrawal	[7]	(51)	(77)
Policyholder Account Balance, Benefit Payment	[2],[7]	(22)	(3)
Policyholder Account Balance, Interest Expense	[7]	16	14
Policyholder Account Balance, Increase (Decrease) from Other Change	[7]	(1)	(9)
Balance – end of period	[7]	2,388	2,556
Policyholder Account Balance, Ending Balance		$ 2,388	$ 2,556
Policyholder Account Balance, Weighted Average Crediting Rate	[4]	2.70%	2.50%
Policyholder Account Balance, Net Amount at Risk	[5]	$ 407	$ 499
Policyholder Account Balance, Cash Surrender Value		$ 2,095	$ 2,239

[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] Primarily comprises unpaid dividends on certain participating policies.

[4] Calculated using actual interest credited for the three months ended March 31, 2025 and 2024, respectively.

[5] 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.

[6] Relates to Huatai Life.

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