Mortgage Loans - Credit Quality Indicators - MF (Details) - Multifamily - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 28,606	$ 50,494
One fiscal year before	54,085	60,908
Two fiscal years before	59,164	64,398
Three fiscal years before	63,772	75,526
Four fiscal years before	74,658	60,850
Prior	196,284	149,178
Total mortgage loans	476,569	461,354
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	28,467	49,944
One fiscal year before	52,958	51,380
Two fiscal years before	49,722	60,563
Three fiscal years before	59,753	72,791
Four fiscal years before	72,329	56,901
Prior	181,698	136,860
Total mortgage loans	444,927	428,439
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	49	4
One fiscal year before	43	11
Two fiscal years before	7	181
Three fiscal years before	369	32
Four fiscal years before	58	46
Prior	128	130
Total mortgage loans	654	404
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	90	521
One fiscal year before	1,080	9,517
Two fiscal years before	9,435	3,654
Three fiscal years before	3,650	2,703
Four fiscal years before	2,271	3,893
Prior	14,451	12,188
Total mortgage loans	30,977	32,476
Substandard | Senior Housing
Financing Receivable, Credit Quality Indicator [Line Items]
Total mortgage loans	4,500	6,900
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	25
One fiscal year before	4	0
Two fiscal years before	0	0
Three fiscal years before	0	0
Four fiscal years before	0	10
Prior	7	0
Total mortgage loans	11	35
Current-year write-offs
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One fiscal year before	34	3
Two fiscal years before	191	4
Three fiscal years before	16	6
Four fiscal years before	21	23
Prior	133	365
Total mortgage loans	$ 395	$ 401