Mortgage Loans - Credit Quality Indicators - SF (Details) - Single-family - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	$ 123,377	$ 123,377	$ 279,314
One fiscal year before	288,643	288,643	489,031
Two fiscal years before	470,931	470,931	1,103,809
Three fiscal years before	1,063,117	1,063,117	890,887
Four fiscal years before	856,529	856,529	155,447
Prior	866,500	866,500	763,925
Total mortgage loans	3,669,097	3,669,097	3,682,413
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff		0	2
One fiscal year, writeoff		15	36
Two fiscal years, writeoff		55	54
Three fiscal years, writeoff		46	46
Four fiscal years, writeoff		16	109
Prior		85	619
Total writeoff		217	866
Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	73,931	73,931	157,317
One fiscal year before	183,004	183,004	354,060
Two fiscal years before	372,256	372,256	1,060,673
Three fiscal years before	1,042,440	1,042,440	887,045
Four fiscal years before	854,097	854,097	154,553
Prior	864,512	864,512	762,320
Total mortgage loans	3,390,240	3,390,240	3,375,968
Greater than 80% and less than or equal to 90%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	19,858	19,858	58,766
One fiscal year before	72,447	72,447	97,186
Two fiscal years before	82,035	82,035	38,932
Three fiscal years before	18,906	18,906	3,432
Four fiscal years before	2,200	2,200	806
Prior	1,565	1,565	1,167
Total mortgage loans	197,011	197,011	200,289
Greater than 90% and less than or equal to 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	29,588	29,588	62,216
One fiscal year before	33,046	33,046	35,990
Two fiscal years before	15,715	15,715	4,014
Three fiscal years before	1,659	1,659	363
Four fiscal years before	194	194	71
Prior	239	239	230
Total mortgage loans	80,441	80,441	102,884
Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0	1,015
One fiscal year before	146	146	1,795
Two fiscal years before	925	925	190
Three fiscal years before	112	112	47
Four fiscal years before	38	38	17
Prior	184	184	208
Total mortgage loans	1,405	1,405	3,272
20- and 30-year or more, amortizing fixed-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	118,980	118,980	268,985
One fiscal year before	278,339	278,339	447,259
Two fiscal years before	431,679	431,679	932,415
Three fiscal years before	901,994	901,994	771,430
Four fiscal years before	745,021	745,021	137,546
Prior	750,603	750,603	650,407
Total mortgage loans	3,226,616	3,226,616	3,208,042
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Current fiscal year, writeoff		0	2
One fiscal year, writeoff		15	35
Two fiscal years, writeoff		54	53
Three fiscal years, writeoff		45	45
Four fiscal years, writeoff		16	108
Prior		72	560
Total writeoff		202	803
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	70,150	70,150	148,641
One fiscal year before	173,891	173,891	314,384
Two fiscal years before	334,255	334,255	889,434
Three fiscal years before	881,378	881,378	767,596
Four fiscal years before	742,596	742,596	136,654
Prior	748,745	748,745	648,964
Total mortgage loans	2,951,015	2,951,015	2,905,673
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	19,486	19,486	57,686
One fiscal year before	71,484	71,484	95,509
Two fiscal years before	80,974	80,974	38,790
Three fiscal years before	18,851	18,851	3,424
Four fiscal years before	2,194	2,194	804
Prior	1,498	1,498	1,082
Total mortgage loans	194,487	194,487	197,295
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	29,344	29,344	61,658
One fiscal year before	32,819	32,819	35,602
Two fiscal years before	15,542	15,542	4,002
Three fiscal years before	1,653	1,653	363
Four fiscal years before	193	193	71
Prior	206	206	189
Total mortgage loans	79,757	79,757	101,885
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	0	1,000
One fiscal year before	145	145	1,764
Two fiscal years before	908	908	189
Three fiscal years before	112	112	47
Four fiscal years before	38	38	17
Prior	154	154	172
Total mortgage loans	1,357	1,357	3,189
15-year or less, amortizing fixed-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	3,282	3,282	7,951
One fiscal year before	7,684	7,684	35,931
Two fiscal years before	33,664	33,664	165,347
Three fiscal years before	155,372	155,372	117,797
Four fiscal years before	109,936	109,936	17,162
Prior	88,225	88,225	84,225
Total mortgage loans	398,163	398,163	428,413
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		1	1
Three fiscal years, writeoff		1	1
Four fiscal years, writeoff		0	1
Prior		2	5
Total writeoff		4	8
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	2,960	2,960	7,110
One fiscal year before	7,189	7,189	35,224
Two fiscal years before	33,391	33,391	165,294
Three fiscal years before	155,353	155,353	117,795
Four fiscal years before	109,935	109,935	17,162
Prior	88,223	88,223	84,222
Total mortgage loans	397,051	397,051	426,807
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	187	187	581
One fiscal year before	430	430	647
Two fiscal years before	255	255	52
Three fiscal years before	18	18	2
Four fiscal years before	1	1	0
Prior	1	1	1
Total mortgage loans	892	892	1,283
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	135	135	259
One fiscal year before	65	65	58
Two fiscal years before	18	18	1
Three fiscal years before	1	1	0
Four fiscal years before	0	0	0
Prior	0	0	1
Total mortgage loans	219	219	319
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	1
One fiscal year before	0	0	2
Two fiscal years before	0	0	0
Three fiscal years before	0	0	0
Four fiscal years before	0	0	0
Prior	1	1	1
Total mortgage loans	1	1	4
Adjustable-rate
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	1,115	1,115	2,378
One fiscal year before	2,620	2,620	5,841
Two fiscal years before	5,588	5,588	6,047
Three fiscal years before	5,751	5,751	1,660
Four fiscal years before	1,572	1,572	712
Prior	9,277	9,277	9,720
Total mortgage loans	25,923	25,923	26,358
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		0	0
Three fiscal years, writeoff		0	0
Four fiscal years, writeoff		0	0
Prior		1	2
Total writeoff		1	3
Adjustable-rate | Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	821	821	1,566
One fiscal year before	1,924	1,924	4,452
Two fiscal years before	4,610	4,610	5,945
Three fiscal years before	5,709	5,709	1,654
Four fiscal years before	1,566	1,566	710
Prior	9,274	9,274	9,716
Total mortgage loans	23,904	23,904	24,043
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	185	185	499
One fiscal year before	533	533	1,030
Two fiscal years before	806	806	90
Three fiscal years before	37	37	6
Four fiscal years before	5	5	2
Prior	2	2	3
Total mortgage loans	1,568	1,568	1,630
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	109	109	299
One fiscal year before	162	162	330
Two fiscal years before	155	155	11
Three fiscal years before	5	5	0
Four fiscal years before	1	1	0
Prior	1	1	1
Total mortgage loans	433	433	641
Adjustable-rate | Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0	14
One fiscal year before	1	1	29
Two fiscal years before	17	17	1
Three fiscal years before	0	0	0
Four fiscal years before	0	0	0
Prior	0	0	0
Total mortgage loans	18	18	44
Other
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0	0
One fiscal year before	0	0	0
Two fiscal years before	0	0	0
Three fiscal years before	0	0	0
Four fiscal years before	0	0	27
Prior	18,395	18,395	19,573
Total mortgage loans	18,395	18,395	19,600
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		10	52
Total writeoff		10	52
Other | Less than or equal to 80%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0	0
One fiscal year before	0	0	0
Two fiscal years before	0	0	0
Three fiscal years before	0	0	0
Four fiscal years before	0	0	27
Prior	18,270	18,270	19,418
Total mortgage loans	18,270	18,270	19,445
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	0
One fiscal year before	0	0	0
Two fiscal years before	0	0	0
Three fiscal years before	0	0	0
Four fiscal years before	0	0	0
Prior	64	64	81
Total mortgage loans	64	64	81
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	0
One fiscal year before	0	0	0
Two fiscal years before	0	0	0
Three fiscal years before	0	0	0
Four fiscal years before	0	0	0
Prior	32	32	39
Total mortgage loans	32	32	39
Other | Greater than 100%
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Current fiscal year	0	0	0
One fiscal year before	0	0	0
Two fiscal years before	0	0	0
Three fiscal years before	0	0	0
Four fiscal years before	0	0	0
Prior	29	29	35
Total mortgage loans	29	29	35
U.S Government
Financing Receivable, before Allowance for Credit Loss, by Origination Year [Abstract]
Total mortgage loans	4,300	$ 4,300	5,500
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Total writeoff	$ 39		$ 7