Variable Interest Entities - Schedule of variable interest entities, credit commitments (Details) - USD ($) $ in Thousands	May 31, 2024	May 31, 2023
Variable Interest Entity [Line Items]
CFC third-party guarantees	$ 1,009,916	$ 796,821
Consolidated variable interest entities
Variable Interest Entity [Line Items]
Total CFC credit commitments	5,000,000	5,500,000
Borrowings payable to CFC	1,532,781	1,428,886
CFC third-party guarantees	43,621	15,263
Other credit enhancements	757	2,038
Total credit enhancements	44,378	17,301
Total outstanding commitments	1,577,159	1,446,187
CFC credit commitments available	$ 3,422,841	$ 4,053,813