Mortgage Loans - Credit Quality Indicators - MF (Details) - Multifamily - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 50,494	$ 59,402
One fiscal year before	60,908	65,786
Two fiscal years before	64,398	76,984
Three fiscal years before	75,526	62,378
Four fiscal years before	60,850	51,270
Prior	149,178	116,402
Total mortgage loans	461,354	432,222
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	49,944	57,976
One fiscal year before	51,380	64,165
Two fiscal years before	60,563	75,468
Three fiscal years before	72,791	59,507
Four fiscal years before	56,901	48,720
Prior	136,860	103,772
Total mortgage loans	428,439	409,608
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	4	11
One fiscal year before	11	41
Two fiscal years before	181	128
Three fiscal years before	32	55
Four fiscal years before	46	54
Prior	130	306
Total mortgage loans	404	595
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	521	1,415
One fiscal year before	9,517	1,580
Two fiscal years before	3,654	1,388
Three fiscal years before	2,703	2,816
Four fiscal years before	3,893	2,488
Prior	12,188	12,324
Total mortgage loans	32,476	22,011
Substandard | Senior Housing
Financing Receivable, Credit Quality Indicator [Line Items]
Total mortgage loans	6,900	9,200
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	25	0
One fiscal year before	0	0
Two fiscal years before	0	0
Three fiscal years before	0	0
Four fiscal years before	10	8
Prior	0	0
Total mortgage loans	35	$ 8
Current-year write-offs
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0
One fiscal year before	3
Two fiscal years before	4
Three fiscal years before	6
Four fiscal years before	23
Prior	365
Total mortgage loans	$ 401