Loans - Schedule of loans outstanding to members and unadvanced commitments by loan type and by member class (Details) - USD ($) $ in Thousands	May 31, 2023	May 31, 2022
Unadvanced Loan Commitments
Total loans outstanding	$ 32,519,349	$ 30,051,354
Deferred loan origination costs	12,737	12,032
Loans to members	$ 32,532,086	$ 30,063,386
% of Total Loans Outstanding	100.00%	100.00%
CFC
Unadvanced Loan Commitments
Total loans outstanding	$ 31,074,687	$ 28,872,875
% of Total Loans Outstanding	96.00%	96.00%
CFC \| Distribution
Unadvanced Loan Commitments
Total loans outstanding	$ 25,437,077	$ 23,844,242
% of Total Loans Outstanding	78.00%	79.00%
CFC \| Power supply
Unadvanced Loan Commitments
Total loans outstanding	$ 5,437,242	$ 4,901,770
% of Total Loans Outstanding	17.00%	17.00%
CFC \| Statewide and associate
Unadvanced Loan Commitments
Total loans outstanding	$ 200,368	$ 126,863
% of Total Loans Outstanding	1.00%	0.00%
NCSC
Unadvanced Loan Commitments
Total loans outstanding	$ 956,874	$ 710,878
% of Total Loans Outstanding	3.00%	2.00%
RTFC
Unadvanced Loan Commitments
Total loans outstanding	$ 487,788	$ 467,601
% of Total Loans Outstanding	1.00%	2.00%
Long-term loans
Unadvanced Loan Commitments
Total loans outstanding	$ 29,396,011	$ 27,772,573
Fixed rate
Unadvanced Loan Commitments
Total loans outstanding	$ 28,371,358	$ 26,952,372
% of Total Loans Outstanding	87.00%	90.00%
Variable rate
Unadvanced Loan Commitments
Total loans outstanding	$ 1,024,653	$ 820,201
% of Total Loans Outstanding	3.00%	2.00%
Lines of credit
Unadvanced Loan Commitments
Total loans outstanding	$ 3,123,338	$ 2,278,781
% of Total Loans Outstanding	10.00%	8.00%
Unamortized loan commitment and origination fees
Unadvanced Loan Commitments
Deferred loan origination costs	$ 12,737	$ 12,032
% of Total Loans Outstanding	0.00%	0.00%

Percentage, before allowance for credit loss, of financing receivable to total financing receivable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (c)
-Publisher SEC

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Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
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Amortized cost excluding accrued interest, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481598/310-20-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Amount of unamortized loan commitment, origination, and other costs (fees) on financing receivable recognized as adjustment to yield. Excludes financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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