Lending Activities - Credit Quality of Commercial Mortgages (Details) - Commercial mortgages $ in Millions	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 61	$ 146
Prior year	48	494
Two years prior	249	200
Three years prior	254	612
Four years prior	618	79
Five years & beyond prior	1,799	1,774
Total	$ 3,029	$ 3,305
Weighted average debt service coverage ratio	1.8	1.8
Weighted average loan-to-value ratio (as a percent)	69.00%	65.00%
Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 61	$ 107
Prior year	48	433
Two years prior	211	177
Three years prior	177	485
Four years prior	498	71
Five years & beyond prior	1,144	1,012
Total	2,139	2,285
65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
Prior year	0	40
Two years prior	33	0
Three years prior	0	54
Four years prior	57	0
Five years & beyond prior	346	317
Total	436	411
76% to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
Prior year	0	0
Two years prior	0	0
Three years prior	0	31
Four years prior	0	0
Five years & beyond prior	38	51
Total	38	82
Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	39
Prior year	0	21
Two years prior	5	23
Three years prior	77	42
Four years prior	63	8
Five years & beyond prior	271	394
Total	416	527
Greater than 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	61	120
Prior year	29	484
Two years prior	239	185
Three years prior	231	563
Four years prior	581	79
Five years & beyond prior	1,596	1,482
Total	2,737	2,913
1.00 - 1.20X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	26
Prior year	19	10
Two years prior	10	15
Three years prior	23	17
Four years prior	32	0
Five years & beyond prior	54	49
Total	138	117
Less than 1.00X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
Prior year	0	0
Two years prior	0	0
Three years prior	0	32
Four years prior	5	0
Five years & beyond prior	149	243
Total	$ 154	$ 275