Mortgage Loans - Credit Quality Indicators - SF (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total mortgage loans	$ 4,050,517	$ 3,968,737
Single-family
Financing Receivable, Credit Quality Indicator [Line Items]
2022	147,107	1,200,915
2021	1,259,603	1,082,870
2020	1,041,539	207,663
2019	192,000	100,239
2018	91,206	135,670
Prior	902,241	829,967
Total mortgage loans	3,633,696	3,557,324
Single-family | Estimated mark-to-market loan-to-value ratio less than or equal to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	111,735	1,001,159
2021	1,086,761	1,040,601
2020	1,019,238	204,398
2019	189,650	98,924
2018	90,177	134,953
Prior	899,189	826,785
Total mortgage loans	3,396,750	3,306,820
Single-family | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	13,342	132,354
2021	133,758	39,973
2020	20,376	2,712
2019	1,866	1,067
2018	850	632
Prior	2,017	1,972
Total mortgage loans	172,209	178,710
Single-family | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	22,030	67,381
2021	39,037	2,284
2020	1,914	544
2019	474	231
2018	163	60
Prior	521	597
Total mortgage loans	64,139	71,097
Single-family | Estimated mark-to-market loan-to-value ratio greater than 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	21
2021	47	12
2020	11	9
2019	10	17
2018	16	25
Prior	514	613
Total mortgage loans	598	697
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	126,719	994,858
2021	1,048,729	923,269
2020	889,296	181,151
2019	167,489	89,126
2018	81,082	111,760
Prior	732,785	668,941
Total mortgage loans	3,046,100	2,969,105
Single-family | 20- and 30-year or more, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio less than or equal to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	92,062	798,830
2021	878,578	881,290
2020	867,141	177,909
2019	165,154	87,825
2018	80,064	111,059
Prior	730,193	666,327
Total mortgage loans	2,813,192	2,723,240
Single-family | 20- and 30-year or more, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	12,914	129,340
2021	131,409	39,689
2020	20,233	2,689
2019	1,851	1,056
2018	842	622
Prior	1,786	1,687
Total mortgage loans	169,035	175,083
Single-family | 20- and 30-year or more, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	21,743	66,667
2021	38,695	2,278
2020	1,911	544
2019	474	229
2018	161	57
Prior	405	460
Total mortgage loans	63,389	70,235
Single-family | 20- and 30-year or more, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio greater than 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	21
2021	47	12
2020	11	9
2019	10	16
2018	15	22
Prior	401	467
Total mortgage loans	484	547
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	19,453	199,318
2021	203,654	157,340
2020	150,110	25,406
2019	23,507	9,600
2018	8,766	20,720
Prior	129,304	121,043
Total mortgage loans	534,794	533,427
Single-family | 15-year or less, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio less than or equal to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	18,861	196,163
2021	201,447	157,076
2020	149,981	25,390
2019	23,495	9,595
2018	8,763	20,715
Prior	129,292	121,027
Total mortgage loans	531,839	529,966
Single-family | 15-year or less, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	357	2,576
2021	1,933	259
2020	127	16
2019	12	4
2018	2	2
Prior	5	7
Total mortgage loans	2,436	2,864
Single-family | 15-year or less, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	235	579
2021	274	5
2020	2	0
2019	0	1
2018	1	1
Prior	2	4
Total mortgage loans	514	590
Single-family | 15-year or less, amortizing fixed-rate | Estimated mark-to-market loan-to-value ratio greater than 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	2
Prior	5	5
Total mortgage loans	5	7
Single-family | Adjustable-rate
Financing Receivable, Credit Quality Indicator [Line Items]
2022	935	6,739
2021	7,220	2,261
2020	2,133	1,072
2019	972	1,240
2018	1,102	2,526
Prior	13,829	12,504
Total mortgage loans	26,191	26,342
Single-family | Adjustable-rate | Estimated mark-to-market loan-to-value ratio less than or equal to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	812	6,166
2021	6,736	2,235
2020	2,116	1,065
2019	969	1,236
2018	1,098	2,524
Prior	13,825	12,501
Total mortgage loans	25,556	25,727
Single-family | Adjustable-rate | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	71	438
2021	416	25
2020	16	7
2019	3	4
2018	4	2
Prior	3	3
Total mortgage loans	513	479
Single-family | Adjustable-rate | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	52	135
2021	68	1
2020	1	0
2019	0	0
2018	0	0
Prior	1	0
Total mortgage loans	122	136
Single-family | Adjustable-rate | Estimated mark-to-market loan-to-value ratio greater than 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Total mortgage loans	0	0
Single-family | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	34
2019	32	273
2018	256	664
Prior	26,323	27,479
Total mortgage loans	26,611	28,450
Single-family | Other | Estimated mark-to-market loan-to-value ratio less than or equal to 80%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	34
2019	32	268
2018	252	655
Prior	25,879	26,930
Total mortgage loans	26,163	27,887
Single-family | Other | Estimated mark-to-market loan-to-value ratio greater than 80% and less than or equal to 90%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	3
2018	2	6
Prior	223	275
Total mortgage loans	225	284
Single-family | Other | Estimated mark-to-market loan-to-value ratio greater than 90% and less than or equal to 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	1
2018	1	2
Prior	113	133
Total mortgage loans	114	136
Single-family | Other | Estimated mark-to-market loan-to-value ratio greater than 100%
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	1
2018	1	1
Prior	108	141
Total mortgage loans	109	143
Single-family | U.S Government
Financing Receivable, Credit Quality Indicator [Line Items]
Total mortgage loans	$ 9,200	$ 9,500