Policyholders' account balances (Guaranteed Minimum Crediting Rates) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	$ 3,215	$ 3,140	$ 2,749	$ 2,766
Universal Life
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,801	1,719	1,659	1,612
Universal Life | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	495		271
Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	50		211
Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	382		447
Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	874		730
Insurance, Other
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,414	1,421	1,090	$ 1,154
Insurance, Other | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	440		124
Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	550		521
Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	189		209
Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	235		236
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Universal Life
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,259		1,144
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Universal Life | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	4		4
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0		0
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	382		410
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	873		730
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Insurance, Other
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,404		1,086
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Insurance, Other | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	430		120
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	550		521
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	189		209
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	235		236
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Universal Life
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	521		484
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Universal Life | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	471		236
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	50		211
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0		37
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0		$ 0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Universal Life
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	21	31
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Universal Life | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	20	31
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0	0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0	0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Universal Life | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1	0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Insurance, Other
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	10	4
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Insurance, Other | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	10	4
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0	0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0	0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Insurance, Other | Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	$ 0	$ 0
Minimum | Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate	2.01%
Minimum | Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate	4.00%
Maximum | Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate	2.00%
Maximum | Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate	4.00%