Mortgage Loans - Credit Quality Indicators - MF (Details) - Multifamily - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 39,088	$ 59,402
One fiscal year before	61,071	65,786
Two fiscal years before	64,639	76,984
Three fiscal years before	75,932	62,378
Four fiscal years before	61,092	51,270
Prior	153,806	116,402
Total mortgage loans	455,628	432,222
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	39,087	57,976
One fiscal year before	53,256	64,165
Two fiscal years before	60,621	75,468
Three fiscal years before	73,279	59,507
Four fiscal years before	57,342	48,720
Prior	138,908	103,772
Total mortgage loans	422,493	409,608
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	11
One fiscal year before	8	41
Two fiscal years before	114	128
Three fiscal years before	53	55
Four fiscal years before	19	54
Prior	298	306
Total mortgage loans	492	595
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	1,415
One fiscal year before	7,807	1,580
Two fiscal years before	3,904	1,388
Three fiscal years before	2,600	2,816
Four fiscal years before	3,726	2,488
Prior	14,600	12,324
Total mortgage loans	32,638	22,011
Substandard | Senior Housing
Financing Receivable, Credit Quality Indicator [Line Items]
Total mortgage loans	9,100	9,200
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One fiscal year before	0	0
Two fiscal years before	0	0
Three fiscal years before	0	0
Four fiscal years before	5	8
Prior	0	0
Total mortgage loans	5	$ 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	0
Three fiscal years before	7
Four fiscal years before	23
Prior	273
Total mortgage loans	$ 306