Policyholders' account balances (Guaranteed Minimum Crediting Rates) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	$ 7,560	$ 7,462	$ 3,178
Universal Life
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,840		1,208
Universal Life | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	563		544
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	461		345
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	767		312
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	49		7
Annuities [Member]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	2,484
Annuities [Member] | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	859
Annuities [Member] | 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
Annuities [Member] | 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	1,624
Annuities [Member] | 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
Insurance, Other
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	2,556		1,385
Insurance, Other | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	1,167		835
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	613		43
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	243		212
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	533		295
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	570		494
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	482		455
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	39		32
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	49		7
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Annuities [Member]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	2,345
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Annuities [Member] | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	720
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Annuities [Member] | 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
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Annuities [Member] | 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	1,624
Policyholder account balance, guaranteed minimum credit rating, range from 0000 to 0200 | Annuities [Member] | 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
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	1,565		953
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	789		446
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	0		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 0051 to 0150
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	243		212
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	533		295
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	1,256		694
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	67		69
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	461		345
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	728		280
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 credit rating, range from 0201 to 0400 | Annuities [Member]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	139
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Annuities [Member] | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	139
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Annuities [Member] | 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
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Annuities [Member] | 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
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Annuities [Member] | 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
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Insurance, Other
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	991		427
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | Insurance, Other | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	378		384
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | 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	613		43
Policyholder account balance, guaranteed minimum credit rating, range from 0201 to 0400 | 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 credit rating, range from 0201 to 0400 | 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
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	14		20
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	14		20
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	0		0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Annuities [Member]
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Annuities [Member] | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance	0
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Annuities [Member] | 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
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Annuities [Member] | 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
Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater | Annuities [Member] | 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
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	0		5
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	0		5
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%