Variable Interest Entities - Information on CFCs Credit Commitments to NCSC and RTFC (Details) - USD ($) $ in Thousands		Nov. 30, 2019	May 31, 2019
Variable Interest Entity [Line Items]
CFC third-party guarantees		$ 794,723	$ 837,435
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
CFC credit commitments		5,500,000	5,500,000
Borrowings payable to CFC	[1]	1,037,863	1,059,629
CFC third-party guarantees		12,591	10,091
Other credit enhancements		8,958	14,251
Total credit enhancements	[2]	21,549	24,342
CFC available credit commitments		1,059,412	1,083,971
CFC available credit commitments		$ 4,440,588	$ 4,416,029

[1] Borrowings payable to CFC are eliminated in consolidation.

[2] Excludes interest due on these instruments.