Variable Interest Entities - Information on CFCs Credit Commitments to NCSC and RTFC (Details) - USD ($) $ in Thousands	Feb. 28, 2022	May 31, 2021
Variable Interest Entity [Line Items]
CFC third-party guarantees	$ 707,304	$ 689,080
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Total CFC credit commitments	5,500,000	5,500,000
Borrowings payable to CFC	1,166,731	1,107,185
CFC third-party guarantees	25,442	16,550
Other credit enhancements	6,273	8,386
Total credit enhancements	31,715	24,936
Total outstanding commitments	1,198,446	1,132,121
CFC credit commitments available	$ 4,301,554	$ 4,367,879