Variable Interest Entities - Information on CFCs Credit Commitments to NCSC and RTFC (Details) - USD ($) $ in Thousands	Nov. 30, 2021	May 31, 2021
Variable Interest Entity [Line Items]
CFC third-party guarantees	$ 657,981	$ 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	1,130,018	1,107,185
CFC third-party guarantees	23,049	16,550
Other credit enhancements	7,578	8,386
Total credit enhancements	30,627	24,936
Total outstanding commitments	1,160,645	1,132,121
CFC credit commitments available	$ 4,339,355	$ 4,367,879