Lending Activities - Credit Quality of Commercial Mortgages (Details) - Commercial mortgages $ in Millions	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 146	$ 403
Prior year	494	249
Two years prior	200	648
Three years prior	612	191
Four years prior	79	177
Five years & beyond prior	1,774	2,168
Total	$ 3,305	$ 3,836
Weighted average debt service coverage ratio	1.8	1.8
Weighted average loan-to-value ratio (as a percent)	65.00%	62.00%
Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 107	$ 359
Prior year	433	159
Two years prior	177	492
Three years prior	485	177
Four years prior	71	156
Five years & beyond prior	1,012	1,385
Total	2,285	2,728
65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	10
Prior year	40	15
Two years prior	0	137
Three years prior	54	0
Four years prior	0	21
Five years & beyond prior	317	367
Total	411	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	31	0
Four years prior	0	0
Five years & beyond prior	51	0
Total	82	42
Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	39	34
Prior year	21	43
Two years prior	23	9
Three years prior	42	14
Four years prior	8	0
Five years & beyond prior	394	416
Total	527	516
Greater than 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	120	398
Prior year	484	167
Two years prior	185	394
Three years prior	563	135
Four years prior	79	156
Five years & beyond prior	1,482	1,784
Total	2,913	3,034
1.00 - 1.20X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	26	5
Prior year	10	71
Two years prior	15	254
Three years prior	17	56
Four years prior	0	21
Five years & beyond prior	49	298
Total	117	705
Less than 1.00X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
Prior year	0	11
Two years prior	0	0
Three years prior	32	0
Four years prior	0	0
Five years & beyond prior	243	86
Total	$ 275	$ 97