Farmer Mac Guaranteed Securities and USDA Securities - Schedule of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Institutional Credit
Weighted- Average Yield
Available-for-sale, accrued interest excluded	$ 32,000	$ 32,300
Farmer Mac Guaranteed Securities
Amortized Cost
Due within one year	1,581,119
Due after one year through five years	2,526,845
Due after five years through ten years	922,881
Due after ten years	1,588,026
Debt securities, available-for-sale, amortized cost	6,618,871
Fair Value
Due within one year	1,586,647
Due after one year through five years	2,621,450
Due after five years through ten years	959,208
Due after ten years	1,710,100
Total, Fair Value	$ 6,877,405
Weighted- Average Yield
Due within one year	1.58%
Due after one year through five years	2.51%
Due after five years through ten years	2.05%
Due after ten years	2.47%
Total, Weighted-Average Yield	2.21%
Farmer Mac Guaranteed Securities | Institutional Credit
Amortized Cost
Debt securities, available-for-sale, amortized cost	$ 6,618,871	6,594,992
Fair Value
Total, Fair Value		$ 6,947,701