Mortgage Loans - Credit Quality Indicators - MF (Details) - Multifamily - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 15,280	$ 50,494
One fiscal year before	54,113	60,908
Two fiscal years before	60,162	64,398
Three fiscal years before	64,104	75,526
Four fiscal years before	75,104	60,850
Prior	202,103	149,178
Total mortgage loans	470,866	461,354
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	15,261	49,944
One fiscal year before	53,341	51,380
Two fiscal years before	50,617	60,563
Three fiscal years before	60,102	72,791
Four fiscal years before	72,560	56,901
Prior	186,999	136,860
Total mortgage loans	438,880	428,439
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	19	4
One fiscal year before	0	11
Two fiscal years before	13	181
Three fiscal years before	419	32
Four fiscal years before	14	46
Prior	98	130
Total mortgage loans	563	404
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	521
One fiscal year before	772	9,517
Two fiscal years before	9,520	3,654
Three fiscal years before	3,583	2,703
Four fiscal years before	2,530	3,893
Prior	15,006	12,188
Total mortgage loans	31,411	32,476
Substandard | Senior Housing
Financing Receivable, Credit Quality Indicator [Line Items]
Total mortgage loans	5,100	6,900
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	25
One fiscal year before	0	0
Two fiscal years before	12	0
Three fiscal years before	0	0
Four fiscal years before	0	10
Prior	0	0
Total mortgage loans	12	35
Current-year write-offs
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One fiscal year before	29	3
Two fiscal years before	27	4
Three fiscal years before	11	6
Four fiscal years before	16	23
Prior	88	365
Total mortgage loans	$ 171	$ 401