Policyholders' account balances (Policyholder Account Balance Rollforward) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2025	Jun. 30, 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		475	564
Policyholder Account Balance, Policy Charge	[1]	(61)	(70)
Policyholder Account Balance, Surrender and Withdrawal		(168)	(238)
Policyholder Account Balance, Benefit Payment	[2]	(142)	(138)
Policyholder Account Balance, Interest Expense		81	82
Policyholder Account Balance, Increase (Decrease) from Other Change		81	(377)
Balance – end of period		7,014	6,612
Unearned Revenue Liability		753	675	$ 711	$ 673
Policyholder Account Balance, Other Reconciling Items	[3]	577	500
Policyholder Account Balance, Ending Balance		8,344	7,787
Universal Life
Policyholder Account Balance [Line Items]
Balance – beginning of period		1,809	1,876
Policyholder Account Balance, Premium Received		105	139
Policyholder Account Balance, Policy Charge	[1]	(56)	(65)
Policyholder Account Balance, Surrender and Withdrawal		(57)	(65)
Policyholder Account Balance, Benefit Payment	[2]	(19)	(56)
Policyholder Account Balance, Interest Expense		24	25
Policyholder Account Balance, Increase (Decrease) from Other Change		34	(76)
Balance – end of period		1,840	1,778
Policyholder Account Balance, Ending Balance		$ 1,840	$ 1,778
Policyholder Account Balance, Weighted Average Crediting Rate	[4]	2.60%	2.80%
Policyholder Account Balance, Net Amount at Risk	[5]	$ 11,571	$ 11,987
Policyholder Account Balance, Cash Surrender Value		1,695	1,611
Annuities [Member]
Policyholder Account Balance [Line Items]
Balance – beginning of period	[6]	2,585	2,411
Policyholder Account Balance, Premium Received	[6]	159	208
Policyholder Account Balance, Policy Charge	[1],[6]	0	0
Policyholder Account Balance, Surrender and Withdrawal	[6]	(17)	(20)
Policyholder Account Balance, Benefit Payment	[2],[6]	(77)	(81)
Policyholder Account Balance, Interest Expense	[6]	24	30
Policyholder Account Balance, Increase (Decrease) from Other Change	[6]	22	(27)
Balance – end of period	[6]	2,696	2,521
Policyholder Account Balance, Ending Balance		$ 2,696	$ 2,521
Policyholder Account Balance, Weighted Average Crediting Rate	[4]	1.80%	2.50%
Policyholder Account Balance, Net Amount at Risk	[5]	$ 10	$ 0
Policyholder Account Balance, Cash Surrender Value		1,774	1,618
Insurance, Other
Policyholder Account Balance [Line Items]
Balance – beginning of period	[7]	2,354	2,502
Policyholder Account Balance, Premium Received	[7]	211	217
Policyholder Account Balance, Policy Charge	[1],[7]	(5)	(5)
Policyholder Account Balance, Surrender and Withdrawal	[7]	(94)	(153)
Policyholder Account Balance, Benefit Payment	[2],[7]	(46)	(1)
Policyholder Account Balance, Interest Expense	[7]	33	27
Policyholder Account Balance, Increase (Decrease) from Other Change	[7]	25	(274)
Balance – end of period	[7]	2,478	2,313
Policyholder Account Balance, Ending Balance		$ 2,478	$ 2,313
Policyholder Account Balance, Weighted Average Crediting Rate	[4]	2.90%	2.90%
Policyholder Account Balance, Net Amount at Risk	[5]	$ 378	$ 454
Policyholder Account Balance, Cash Surrender Value		$ 2,175	$ 2,013

[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 six months ended June 30, 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.