Long-Term Debt - Schedule of Long-term Debt Outstanding (Details) - USD ($) $ in Thousands	Feb. 28, 2026	May 31, 2025
Long-term debt
Total	$ 28,908,515	$ 27,163,701
Total collateral trust bonds
Long-term debt
Long-term debt, gross	6,670,191	7,082,711
Unamortized premium (discount), net	(144,219)	(155,393)
Debt issuance costs	(28,473)	(31,616)
Total	6,497,499	6,895,702
Guaranteed Underwriter Program notes payable
Long-term debt
Total	5,743,393	6,456,852
Farmer Mac notes payable
Long-term debt
Total	3,929,086	3,780,461
Total secured notes payable
Long-term debt
Total	9,672,479	10,237,313
Total secured long-term debt
Long-term debt
Total	16,169,978	17,133,015
Medium-term notes sold through dealers
Long-term debt
Long-term debt, gross	12,400,586	9,637,577
Medium-term notes sold to members
Long-term debt
Long-term debt, gross	365,827	419,648
Medium term notes sold through dealers and to members
Long-term debt
Long-term debt, gross	12,766,413	10,057,225
Debt issuance costs	(28,500)	(29,180)
Unamortized premium (discount), net	624	2,641
Total	$ 12,738,537	$ 10,030,686