Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	May 31, 2026 USD ($) class $ / shares	May 31, 2025 USD ($)	May 31, 2024 USD ($)
Summary of Significant Accounting Policies [Line Items]
Number of classes of members | class	2
Restricted cash	$ 8,599	$ 8,410
Accrued interest receivable	240,000	237,000
Placement agent fees income	$ 0	$ 0	$ 0
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities	Other Liabilities
Finance lease liability	$ 7,000	$ 7,000
Interest expenses from finance lease	0	0	0
Variable lease cost	0	0
Net investment in leases	7,000	7,000
Interest income from sales-type lease	0	0	0
Variable lease payment income	0	0	0
Depreciation and amortization	8,000	8,000	7,000
Unamortized capitalized implementation costs	51,000	48,000
Capitalized implementation costs, accumulated amortization	15,000	9,000
Capitalized implementation costs, amortization	$ 6,000	$ 5,000	$ 3,000
Effective percentage of tax rate	21.00%	21.00%	21.00%
Minimum
Summary of Significant Accounting Policies [Line Items]
Finance lease term	3 years
Sales-type lease term	3 years
Estimated useful lives	3 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Finance lease term	10 years
Sales-type lease term	10 years
Estimated useful lives	40 years
Unadvanced commitments
Summary of Significant Accounting Policies [Line Items]
Loans and leases receivable unadvanced commitments period, maximum	5 years
Unadvanced commitments not subject to material adverse change clauses
Summary of Significant Accounting Policies [Line Items]
Loans and leases receivable unadvanced commitments period, maximum	5 years
CFC | Distribution system members
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share) | $ / shares	$ 1,000
CFC | Service organization members
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share) | $ / shares	200
CFC | Associates
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share) | $ / shares	1,000
NCSC
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share) | $ / shares	$ 100