Lending Activities - Credit Quality of Commercial Mortgages (Details) - Commercial mortgages $ in Millions	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 52	$ 403
Prior year	493	249
Two years prior	242	648
Three years prior	692	191
Four years prior	158	177
Five years & beyond prior	2,091	2,168
Total	$ 3,728	$ 3,836
Weighted average debt service coverage ratio	1.8	1.8
Weighted average loan-to-value ratio (as a percent)	64.00%	62.00%
Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 33	$ 359
Prior year	357	159
Two years prior	154	492
Three years prior	506	177
Four years prior	150	156
Five years & beyond prior	1,400	1,385
Total	2,600	2,728
65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	19	10
Prior year	81	15
Two years prior	46	137
Three years prior	134	0
Four years prior	0	21
Five years & beyond prior	302	367
Total	582	550
76% to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
Prior year	0	32
Two years prior	0	10
Three years prior	0	0
Four years prior	0	0
Five years & beyond prior	62	0
Total	62	42
Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	34
Prior year	55	43
Two years prior	42	9
Three years prior	52	14
Four years prior	8	0
Five years & beyond prior	327	416
Total	484	516
Greater than 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	33	398
Prior year	460	167
Two years prior	183	394
Three years prior	407	135
Four years prior	102	156
Five years & beyond prior	1,719	1,784
Total	2,904	3,034
1.00 - 1.20X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	19	5
Prior year	33	71
Two years prior	48	254
Three years prior	285	56
Four years prior	56	21
Five years & beyond prior	247	298
Total	688	705
Less than 1.00X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
Prior year	0	11
Two years prior	11	0
Three years prior	0	0
Four years prior	0	0
Five years & beyond prior	125	86
Total	$ 136	$ 97