Policyholders' account balances (Guaranteed Minimum Crediting Rates) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	$ 3,178	$ 3,140	$ 2,768	$ 2,766
Universal Life
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,746	1,719	1,650	1,612
Universal Life | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	456		242
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	56		210
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	388		455
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	846		743
Insurance, Other
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,432	$ 1,421	1,118	$ 1,154
Insurance, Other | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	154		0
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	547		530
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	188		219
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	543		369
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	1,237		1,167
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	3		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	388		420
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	846		743
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	1,432		1,118
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	154		0
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	547		530
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	188		219
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	543		369
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	509		483
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	453		238
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	56		210
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		35
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
Minimum | 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	0.00%
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%
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%