Variable Interest Entities - Schedule of variable interest entities, credit commitments (Details) - USD ($) $ in Thousands	May 31, 2023	May 31, 2022
Variable Interest Entity [Line Items]
CFC third-party guarantees	$ 796,821	$ 730,783
Consolidated variable interest entities
Variable Interest Entity [Line Items]
Total CFC credit commitments	5,500,000	5,500,000
Borrowings payable to CFC	1,428,886	1,158,583
CFC third-party guarantees	15,263	23,970
Other credit enhancements	2,038	4,044
Total credit enhancements	17,301	28,014
Total outstanding commitments	1,446,187	1,186,597
CFC credit commitments available	$ 4,053,813	$ 4,313,403