Market risk benefits (MRB Roll-Forward) (Details) - USD ($) $ in Millions			3 Months Ended	12 Months Ended
		Jan. 01, 2021	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Market Risk Benefit [Line Items]
Market Risk Benefit, Liability, beginning of period				$ 800
Market Risk Benefit, Liability, end of period			$ 771	771	$ 800
Market risk benefits gains (losses)				$ (307)	$ 80	$ 91
Minimum
Market Risk Benefit [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate			0.50%	0.50%	0.50%	0.50%
Annuitization rate				0.00%	0.00%	0.00%
Maximum
Market Risk Benefit [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate			30.00%	30.00%	30.40%	31.50%
Annuitization rate				100.00%	100.00%	100.00%
Weighted Average
Market Risk Benefit [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate	[1]		4.00%	4.00%	3.50%	4.80%
Annuitization rate	[1]			4.50%	4.40%	3.60%
Variable Annuity [Member]
Market Risk Benefit [Line Items]
Market Risk Benefit, Liability, end of period		$ 1,163
Long-Duration Insurance, Other | Variable Annuity [Member]
Market Risk Benefit [Line Items]
Market Risk Benefit, Liability, beginning of period		1,163		$ 800	$ 812	$ 1,163
Balance, beginning of period, before effect of changes in the instrument-specific credit risk		$ 1,079		776	755	1,079
Interest rate changes				26	(568)	(157)
Effect of changes in equity markets				(195)	513	(223)
Effect of changes in volatilities				20	27	(65)
Market Risk Benefit, Increase (Decrease) from Actual Policyholder Behavior Different from Expected				18	(13)	42
Market Risk Benefit, Increase (Decrease) from Future Expected Policyholder Behavior Assumption				89	40	24
Effect of timing and all other				15	22	55
Balance, end of period, before effect of changes in the instrument-specific credit risk			$ 749	749	776	755
Effect of changes in the instrument-specific credit risk			22	22	24	57
Market Risk Benefit, Liability, end of period			771	$ 771	$ 800	$ 812
Market risk benefit, weighted-average age of policyholders (age)				74 years	73 years	72 years
Market Risk Benefit, Net Amount at Risk	[2]		1,872	$ 1,872	$ 2,508	$ 1,759
Market Risk Benefits Other Gains (Losses)				$ (334)	$ 106	$ (232)
Long-Duration Insurance, Other | Variable Annuity [Member] | Measurement Input, Annuitization Rate [Member]
Market Risk Benefit [Line Items]
Market Risk Benefit, Increase (Decrease) from Future Expected Policyholder Behavior Assumption			$ 92

[1] The weighted-average lapse and annuitization rates are determined by weighting each treaty's rates by the MRB contract's fair value.

[2] The net amount at risk is defined as the present value of future claim payments assuming policy account values and guaranteed values are fixed at the valuation date, and reinsurance coverage ends at the earlier of the maturity of the underlying variable annuity policy or the reinsurance treaty. No withdrawals, lapses, and mortality improvements are assumed in the projection. GLB-related risks contain conservative mortality and annuitization assumptions.