Lending Activities - Credit Quality of Commercial Mortgages (Details) - Commercial mortgages $ in Millions	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 10	$ 146
Prior year	154	494
Two years prior	512	200
Three years prior	210	612
Four years prior	612	79
Five years & beyond prior	1,794	1,774
Total	$ 3,292	$ 3,305
Weighted average debt service coverage ratio	1.8	1.8
Weighted average loan-to-value ratio (as a percent)	67.00%	65.00%
Less than 65%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	$ 10	$ 107
Prior year	114	433
Two years prior	426	177
Three years prior	187	485
Four years prior	462	71
Five years & beyond prior	1,044	1,012
Total	2,243	2,285
65% to 75%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	0
Prior year	0	40
Two years prior	86	0
Three years prior	0	54
Four years prior	84	0
Five years & beyond prior	316	317
Total	486	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	74	51
Total	74	82
Greater than 80%
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	39
Prior year	40	21
Two years prior	0	23
Three years prior	23	42
Four years prior	66	8
Five years & beyond prior	360	394
Total	489	527
Greater than 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	10	120
Prior year	124	484
Two years prior	502	185
Three years prior	194	563
Four years prior	562	79
Five years & beyond prior	1,521	1,482
Total	2,913	2,913
1.00 - 1.20X
Financing Receivable, Credit Quality Indicator [Line Items]
Current year	0	26
Prior year	30	10
Two years prior	10	15
Three years prior	16	17
Four years prior	18	0
Five years & beyond prior	49	49
Total	123	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	32	0
Five years & beyond prior	224	243
Total	$ 256	$ 275