Mortgage Loans - Credit Quality Indicators - SF (Details) - Single-family - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2025	Dec. 31, 2024
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	$ 119,253	$ 288,639
One fiscal year before	298,617	265,785
Two fiscal years before	248,614	450,253
Three fiscal years before	430,834	1,020,997
Four fiscal years before	981,564	820,495
Prior	1,551,615	812,958
Total mortgage loans	3,630,497	3,659,127
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0	2
One fiscal year, writeoff	19	44
Two fiscal years, writeoff	41	133
Three fiscal years, writeoff	88	116
Four fiscal years, writeoff	51	72
Prior	147	303
Total writeoff	346	670
Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	74,142	165,115
One fiscal year before	186,183	169,482
Two fiscal years before	172,615	359,669
Three fiscal years before	364,430	1,000,638
Four fiscal years before	968,517	818,130
Prior	1,548,169	811,170
Total mortgage loans	3,314,056	3,324,204
Greater than 80% and less than or equal to 90%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	18,486	54,914
One fiscal year before	67,806	67,979
Two fiscal years before	61,051	71,956
Three fiscal years before	54,236	18,388
Four fiscal years before	11,460	2,083
Prior	2,874	1,398
Total mortgage loans	215,913	216,718
Greater than 90% and less than or equal to 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	26,624	68,344
One fiscal year before	44,153	27,646
Two fiscal years before	14,142	16,982
Three fiscal years before	10,642	1,762
Four fiscal years before	1,388	234
Prior	385	233
Total mortgage loans	97,334	115,201
Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1	266
One fiscal year before	475	678
Two fiscal years before	806	1,646
Three fiscal years before	1,526	209
Four fiscal years before	199	48
Prior	187	157
Total mortgage loans	3,194	3,004
20- and 30-year or more, amortizing fixed-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	111,833	278,055
One fiscal year before	287,929	256,538
Two fiscal years before	240,261	413,636
Three fiscal years before	396,744	870,282
Four fiscal years before	840,836	716,979
Prior	1,367,833	711,838
Total mortgage loans	3,245,436	3,247,328
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0	2
One fiscal year, writeoff	19	43
Two fiscal years, writeoff	40	130
Three fiscal years, writeoff	85	114
Four fiscal years, writeoff	50	71
Prior	120	261
Total writeoff	314	621
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	67,747	156,136
One fiscal year before	176,742	161,237
Two fiscal years before	164,943	324,160
Three fiscal years before	331,096	849,984
Four fiscal years before	827,820	714,620
Prior	1,364,477	710,162
Total mortgage loans	2,932,825	2,916,299
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	17,824	53,904
One fiscal year before	66,837	67,163
Two fiscal years before	60,483	71,059
Three fiscal years before	53,627	18,333
Four fiscal years before	11,436	2,078
Prior	2,826	1,338
Total mortgage loans	213,033	213,875
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	26,261	67,749
One fiscal year before	43,876	27,468
Two fiscal years before	14,036	16,801
Three fiscal years before	10,517	1,757
Four fiscal years before	1,382	233
Prior	363	205
Total mortgage loans	96,435	114,213
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	1	266
One fiscal year before	474	670
Two fiscal years before	799	1,616
Three fiscal years before	1,504	208
Four fiscal years before	198	48
Prior	167	133
Total mortgage loans	3,143	2,941
15-year or less, amortizing fixed-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	5,723	8,407
One fiscal year before	8,506	6,793
Two fiscal years before	6,049	31,325
Three fiscal years before	29,072	145,266
Four fiscal years before	135,553	102,032
Prior	159,233	75,904
Total mortgage loans	344,136	369,727
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0	0
One fiscal year, writeoff	0	1
Two fiscal years, writeoff	1	2
Three fiscal years, writeoff	2	2
Four fiscal years, writeoff	1	1
Prior	2	4
Total writeoff	6	10
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	5,095	7,508
One fiscal year before	7,838	6,455
Two fiscal years before	5,876	31,140
Three fiscal years before	28,986	145,254
Four fiscal years before	135,549	102,032
Prior	159,233	75,904
Total mortgage loans	342,577	368,293
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	401	576
One fiscal year before	537	314
Two fiscal years before	165	168
Three fiscal years before	75	11
Four fiscal years before	4	0
Prior	0	0
Total mortgage loans	1,182	1,069
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	227	323
One fiscal year before	131	24
Two fiscal years before	8	16
Three fiscal years before	10	1
Four fiscal years before	0	0
Prior	0	0
Total mortgage loans	376	364
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	0
One fiscal year before	0	0
Two fiscal years before	0	1
Three fiscal years before	1	0
Four fiscal years before	0	0
Prior	0	0
Total mortgage loans	1	1
Adjustable-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,697	2,177
One fiscal year before	2,182	2,454
Two fiscal years before	2,304	5,292
Three fiscal years before	5,018	5,449
Four fiscal years before	5,175	1,484
Prior	8,685	8,162
Total mortgage loans	25,061	25,018
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0	0
One fiscal year, writeoff	0	0
Two fiscal years, writeoff	0	1
Three fiscal years, writeoff	1	0
Four fiscal years, writeoff	0	0
Prior	0	1
Total writeoff	1	2
Adjustable-rate | Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,300	1,471
One fiscal year before	1,603	1,790
Two fiscal years before	1,796	4,369
Three fiscal years before	4,348	5,400
Four fiscal years before	5,148	1,478
Prior	8,679	8,159
Total mortgage loans	22,874	22,667
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	261	434
One fiscal year before	432	502
Two fiscal years before	403	729
Three fiscal years before	534	44
Four fiscal years before	20	5
Prior	5	2
Total mortgage loans	1,655	1,716
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	136	272
One fiscal year before	146	154
Two fiscal years before	98	165
Three fiscal years before	115	4
Four fiscal years before	6	1
Prior	1	1
Total mortgage loans	502	597
Adjustable-rate | Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0
One fiscal year before	1	8
Two fiscal years before	7	29
Three fiscal years before	21	1
Four fiscal years before	1	0
Prior	0	0
Total mortgage loans	30	38
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	0
Four fiscal years before	0	0
Prior	15,864	17,054
Total mortgage loans	15,864	17,054
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff	0	0
One fiscal year, writeoff	0	0
Two fiscal years, writeoff	0	0
Three fiscal years, writeoff	0	0
Four fiscal years, writeoff	0	0
Prior	25	37
Total writeoff	25	37
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	0
Four fiscal years before	0	0
Prior	15,780	16,945
Total mortgage loans	15,780	16,945
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	0
Prior	43	58
Total mortgage loans	43	58
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	0
Prior	21	27
Total mortgage loans	21	27
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	20	24
Total mortgage loans	20	24
U.S Government
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Total mortgage loans	3,100	3,600
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total writeoff	$ 4	$ 47