Farmer Mac Guaranteed Securities and USDA Securities - Schedule of Available-for-sale Securities (Details) - Farmer Mac Guaranteed Securities $ in Thousands	Dec. 31, 2019 USD ($)
Amortized Cost
Due within one year	$ 781,341
Due after one year through five years	3,455,526
Due after five years through ten years	1,240,670
Due after ten years	1,539,434
Amortized Cost	7,016,971
Fair Value
Due within one year	781,680
Due after one year through five years	3,512,820
Due after five years through ten years	1,271,208
Due after ten years	1,577,317
Total	$ 7,143,025
Weighted- Average Yield
Due within one year	2.35%
Due after one year through five years	2.93%
Due after five years through ten years	2.92%
Due after ten years	3.30%
Total	2.94%