Farmer Mac Guaranteed Securities and USDA Securities - Schedule of Held-to-maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
AgVantage
Weighted- Average Yield
Held-to-maturity, accrued interest excluded	$ 42,100	$ 44,700
Farmer Mac Guaranteed Securities and USDA Securities
Amortized Cost
Due within one year	1,146,637
Due after one year through five years	904,570
Due after five years through ten years	253,388
Due after ten years	2,165,107
Amortized Cost	4,469,702	$ 3,649,538
Fair Value
Due within one year	1,146,747
Due after one year through five years	902,695
Due after five years through ten years	262,906
Due after ten years	2,251,458
Total	$ 4,563,806
Weighted- Average Yield
Due within one year	0.65%
Due after one year through five years	2.09%
Due after five years through ten years	2.76%
Due after ten years	3.15%
Total	2.26%