Mortgage Loans - Credit Quality Indicators - MF (Details) - Multifamily - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 34,611	$ 67,881
One fiscal year before	77,686	54,475
Two fiscal years before	53,953	52,867
Three fiscal years before	51,190	56,208
Four fiscal years before	54,719	61,785
Prior	261,871	230,737
Total mortgage loans	534,030	523,953
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	34,557	67,503
One fiscal year before	76,765	52,368
Two fiscal years before	50,995	48,990
Three fiscal years before	46,902	49,486
Four fiscal years before	48,779	58,248
Prior	246,517	218,704
Total mortgage loans	504,515	495,299
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	28	0
One fiscal year before	21	187
Two fiscal years before	67	124
Three fiscal years before	128	155
Four fiscal years before	195	246
Prior	764	793
Total mortgage loans	1,203	1,505
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	26	378
One fiscal year before	887	1,920
Two fiscal years before	2,891	3,753
Three fiscal years before	4,160	6,567
Four fiscal years before	5,745	3,291
Prior	14,590	11,239
Total mortgage loans	28,299	27,148
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One fiscal year before	13	0
Two fiscal years before	0	0
Three fiscal years before	0	0
Four fiscal years before	0	0
Prior	0	1
Total mortgage loans	13	1
Current-year write-offs
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One fiscal year before	0	17
Two fiscal years before	36	111
Three fiscal years before	171	108
Four fiscal years before	123	66
Prior	274	168
Total mortgage loans	$ 604	$ 470