Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)		12 Months Ended
		May 31, 2021	May 31, 2020	May 31, 2019
Summary of Significant Accounting Policies [Line Items]
Repossessed Assets		$ 0	$ 0
Restricted cash	[1]	8,298,000	8,647,000
Depreciation and amortization		7,959,000	9,238,000	$ 9,305,000
Deferred income		51,198,000	59,303,000
Deferred Loan Conversion Fees		45,000,000	53,000,000
Gain on sale of land		0	(7,713,000)	0
Asset Impairment Charges		0	31,284,000	$ 0
Retained equity		1,374,973,000	628,031,000
Financing Receivable, Accrued Interest, before Allowance for Credit Loss		93,000,000	$ 96,000,000
Cumulative effect from adoption of new accounting standard | Accounting Standards Update 2016-13
Summary of Significant Accounting Policies [Line Items]
Retained equity		$ 4,000,000
Maximum
Summary of Significant Accounting Policies [Line Items]
Estimated useful lives		40 years
Minimum
Summary of Significant Accounting Policies [Line Items]
Estimated useful lives		3 years
RTFC
Summary of Significant Accounting Policies [Line Items]
Effective percentage of tax rate		21.00%	21.00%	21.00%
RTFC | Minimum
Summary of Significant Accounting Policies [Line Items]
Percentage of income from patronage sources allocated to borrowers to be retired in cash prior to filing the applicable tax return		20.00%
NCSC
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share)		$ 100
Deferred Tax Assets, Net		$ 2,000,000	$ 3,000,000
Effective percentage of tax rate		21.00%	21.00%	21.00%
Distribution system members | CFC
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share)		$ 1,000
Service organization members | CFC
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share)		200
Associates | CFC
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share)		1,000
Associates | RTFC
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share)		100
Voting members | RTFC
Summary of Significant Accounting Policies [Line Items]
Membership fees (in dollars per share)		$ 1,000
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
Unadvanced commitments
Summary of Significant Accounting Policies [Line Items]
Loans and Leases Receivable Unadvanced Commitments Period Maximum		5 years

[1] (1) Restricted cash consists primarily of member funds held in escrow for certain specifically designed cooperative programs.