Mortgage Loans - Credit Quality Indicators - SF (Details) - Single-family - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	$ 42,464	$ 497,393
One fiscal year before	514,249	1,185,382
Two fiscal years before	1,166,789	963,992
Three fiscal years before	946,781	171,549
Four fiscal years before	167,749	79,469
Prior	843,532	790,243
Total mortgage loans	3,681,564	3,688,028
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0
One fiscal year, writeoff	3
Two fiscal years, writeoff	10
Three fiscal years, writeoff	5
Four fiscal years, writeoff	2
Prior	20
Total writeoff	40
Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	24,255	323,058
One fiscal year before	320,942	1,088,871
Two fiscal years before	1,064,568	956,653
Three fiscal years before	938,542	170,156
Four fiscal years before	166,253	78,758
Prior	841,031	788,467
Total mortgage loans	3,355,591	3,405,963
Greater than 80% and less than or equal to 90%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	6,839	87,240
One fiscal year before	97,527	86,981
Two fiscal years before	87,939	5,949
Three fiscal years before	6,874	1,158
Four fiscal years before	1,298	620
Prior	1,815	1,196
Total mortgage loans	202,292	183,144
Greater than 90% and less than or equal to 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	11,370	85,861
One fiscal year before	90,244	9,321
Two fiscal years before	13,770	1,334
Three fiscal years before	1,282	217
Four fiscal years before	177	79
Prior	377	281
Total mortgage loans	117,220	97,093
Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	1,234
One fiscal year before	5,536	209
Two fiscal years before	512	56
Three fiscal years before	83	18
Four fiscal years before	21	12
Prior	309	299
Total mortgage loans	6,461	1,828
20- and 30-year or more, amortizing fixed-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	40,231	452,015
One fiscal year before	468,707	992,804
Two fiscal years before	979,383	827,745
Three fiscal years before	814,719	150,454
Four fiscal years before	147,469	71,013
Prior	706,198	652,823
Total mortgage loans	3,156,707	3,146,854
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0
One fiscal year, writeoff	3
Two fiscal years, writeoff	10
Three fiscal years, writeoff	5
Four fiscal years, writeoff	2
Prior	15
Total writeoff	35
20- and 30-year or more, amortizing fixed-rate | Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	22,412	281,257
One fiscal year before	279,467	896,977
Two fiscal years before	877,834	820,452
Three fiscal years before	806,520	149,067
Four fiscal years before	145,978	70,306
Prior	703,955	651,297
Total mortgage loans	2,836,166	2,869,356
20- and 30-year or more, amortizing fixed-rate | Greater than 80% and less than or equal to 90%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	6,625	84,864
One fiscal year before	94,815	86,335
Two fiscal years before	87,316	5,904
Three fiscal years before	6,836	1,152
Four fiscal years before	1,293	618
Prior	1,682	1,062
Total mortgage loans	198,567	179,935
20- and 30-year or more, amortizing fixed-rate | Greater than 90% and less than or equal to 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	11,194	84,664
One fiscal year before	88,919	9,284
Two fiscal years before	13,722	1,333
Three fiscal years before	1,280	217
Four fiscal years before	177	77
Prior	315	224
Total mortgage loans	115,607	95,799
20- and 30-year or more, amortizing fixed-rate | Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	1,230
One fiscal year before	5,506	208
Two fiscal years before	511	56
Three fiscal years before	83	18
Four fiscal years before	21	12
Prior	246	240
Total mortgage loans	6,367	1,764
15-year or less, amortizing fixed-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,659	39,748
One fiscal year before	39,372	185,938
Two fiscal years before	180,887	134,370
Three fiscal years before	130,238	20,242
Four fiscal years before	19,453	7,324
Prior	103,944	103,846
Total mortgage loans	475,553	491,468
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0
One fiscal year, writeoff	0
Two fiscal years, writeoff	0
Three fiscal years, writeoff	0
Four fiscal years, writeoff	0
Prior	1
Total writeoff	1
15-year or less, amortizing fixed-rate | Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,494	37,830
One fiscal year before	37,382	185,511
Two fiscal years before	180,495	134,336
Three fiscal years before	130,210	20,239
Four fiscal years before	19,451	7,324
Prior	103,939	103,841
Total mortgage loans	472,971	489,081
15-year or less, amortizing fixed-rate | Greater than 80% and less than or equal to 90%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	86	1,363
One fiscal year before	1,475	410
Two fiscal years before	372	33
Three fiscal years before	27	3
Four fiscal years before	2	0
Prior	2	2
Total mortgage loans	1,964	1,811
15-year or less, amortizing fixed-rate | Greater than 90% and less than or equal to 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	79	552
One fiscal year before	509	16
Two fiscal years before	20	1
Three fiscal years before	1	0
Four fiscal years before	0	0
Prior	1	1
Total mortgage loans	610	570
15-year or less, amortizing fixed-rate | Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	3
One fiscal year before	6	1
Two fiscal years before	0	0
Three fiscal years before	0	0
Four fiscal years before	0	0
Prior	2	2
Total mortgage loans	8	6
Adjustable-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	574	5,630
One fiscal year before	6,170	6,640
Two fiscal years before	6,519	1,877
Three fiscal years before	1,824	824
Four fiscal years before	799	908
Prior	11,538	11,229
Total mortgage loans	27,424	27,108
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0
One fiscal year, writeoff	0
Two fiscal years, writeoff	0
Three fiscal years, writeoff	0
Four fiscal years, writeoff	0
Prior	0
Total writeoff	0
Adjustable-rate | Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	349	3,971
One fiscal year before	4,093	6,383
Two fiscal years before	6,239	1,865
Three fiscal years before	1,812	821
Four fiscal years before	796	906
Prior	11,533	11,226
Total mortgage loans	24,822	25,172
Adjustable-rate | Greater than 80% and less than or equal to 90%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	128	1,013
One fiscal year before	1,237	236
Two fiscal years before	251	12
Three fiscal years before	11	3
Four fiscal years before	3	1
Prior	4	3
Total mortgage loans	1,634	1,268
Adjustable-rate | Greater than 90% and less than or equal to 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	97	645
One fiscal year before	816	21
Two fiscal years before	28	0
Three fiscal years before	1	0
Four fiscal years before	0	1
Prior	1	0
Total mortgage loans	943	667
Adjustable-rate | Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	1
One fiscal year before	24	0
Two fiscal years before	1	0
Three fiscal years before	0	0
Four fiscal years before	0	0
Prior	0	0
Total mortgage loans	25	1
Other
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0
One fiscal year before	0	0
Two fiscal years before	0	0
Three fiscal years before	0	29
Four fiscal years before	28	224
Prior	21,852	22,345
Total mortgage loans	21,880	22,598
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0
One fiscal year, writeoff	0
Two fiscal years, writeoff	0
Three fiscal years, writeoff	0
Four fiscal years, writeoff	0
Prior	4
Total writeoff	4
Other | Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0
One fiscal year before	0	0
Two fiscal years before	0	0
Three fiscal years before	0	29
Four fiscal years before	28	222
Prior	21,604	22,103
Total mortgage loans	21,632	22,354
Other | Greater than 80% and less than or equal to 90%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
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	0	1
Prior	127	129
Total mortgage loans	127	130
Other | Greater than 90% and less than or equal to 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
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	0	1
Prior	60	56
Total mortgage loans	60	57
Other | Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
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	0	0
Prior	61	57
Total mortgage loans	61	57
U.S Government
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Total mortgage loans	8,500	$ 9,500
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total writeoff	$ 2