Guarantees - Unpaid Principal Balances by Delinquency Status (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Guarantor Obligations [Line Items]
Total	$ 7,796,712	$ 7,261,933
Current
Guarantor Obligations [Line Items]
Total	8,712,035	8,315,566
Total Past Due
Guarantor Obligations [Line Items]
Total	17,444	6,286
30-59 Days
Guarantor Obligations [Line Items]
Total	11,501	4,582
60-89 Days
Guarantor Obligations [Line Items]
Total	525	632
90 Days and Greater
Guarantor Obligations [Line Items]
Total	5,418	1,072
Farm & Ranch
Guarantor Obligations [Line Items]
Total	6,601,205	6,176,438
Farm & Ranch | Current
Guarantor Obligations [Line Items]
Total	6,475,467	6,055,154
Farm & Ranch | Total Past Due
Guarantor Obligations [Line Items]
Total	7,444	6,286
Farm & Ranch | 30-59 Days
Guarantor Obligations [Line Items]
Total	1,501	4,582
Farm & Ranch | 60-89 Days
Guarantor Obligations [Line Items]
Total	525	632
Farm & Ranch | 90 Days and Greater
Guarantor Obligations [Line Items]
Total	5,418	1,072
Rural Utilities
Guarantor Obligations [Line Items]
Total	2,246,568	2,260,412
Rural Utilities | Current
Guarantor Obligations [Line Items]
Total	2,236,568	2,260,412
Rural Utilities | Total Past Due
Guarantor Obligations [Line Items]
Total	10,000	0
Rural Utilities | 30-59 Days
Guarantor Obligations [Line Items]
Total	10,000	0
Rural Utilities | 60-89 Days
Guarantor Obligations [Line Items]
Total	0	0
Rural Utilities | 90 Days and Greater
Guarantor Obligations [Line Items]
Total	0	0
LTSPCs and Farmer Mac Guaranteed Securities | Farm & Ranch
Guarantor Obligations [Line Items]
Total	2,454,947	2,404,743
LTSPCs and Farmer Mac Guaranteed Securities | Farm & Ranch | Current
Guarantor Obligations [Line Items]
Total	2,440,348	2,389,777
LTSPCs and Farmer Mac Guaranteed Securities | Farm & Ranch | Total Past Due
Guarantor Obligations [Line Items]
Total	14,599	14,966
LTSPCs and Farmer Mac Guaranteed Securities | Farm & Ranch | 30-59 Days
Guarantor Obligations [Line Items]
Total	3,853	2,189
LTSPCs and Farmer Mac Guaranteed Securities | Farm & Ranch | 60-89 Days
Guarantor Obligations [Line Items]
Total	4,459	1,344
LTSPCs and Farmer Mac Guaranteed Securities | Farm & Ranch | 90 Days and Greater
Guarantor Obligations [Line Items]
Total	6,287	11,433
LTSPCs | Rural Utilities
Guarantor Obligations [Line Items]
Total	533,459	556,425
LTSPCs | Rural Utilities | Current
Guarantor Obligations [Line Items]
Total	533,459	556,425
LTSPCs | Rural Utilities | Total Past Due
Guarantor Obligations [Line Items]
Total	0	0
LTSPCs | Rural Utilities | 30-59 Days
Guarantor Obligations [Line Items]
Total	0	0
LTSPCs | Rural Utilities | 60-89 Days
Guarantor Obligations [Line Items]
Total	0	0
LTSPCs | Rural Utilities | 90 Days and Greater
Guarantor Obligations [Line Items]
Total	$ 0	$ 0