Financing Receivable, Allowance for Credit Loss, Additional Information1 [Abstract]

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Percentage of allowance for credit loss to total financing receivable outstanding.

+ References

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

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- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

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- Definition

Amount of allowance for credit loss on financing receivable evaluated on collective basis. Excludes financing receivable evaluated on individual basis.

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- Definition

Amount of allowance for credit loss on financing receivable evaluated on individual basis. Excludes financing receivable evaluated on collective basis.

+ References

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Balance Type:	credit
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- Definition

Amount of financing receivable collectively evaluated for credit loss. Excludes financing receivable individually evaluated for credit loss.

+ References

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- Definition

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/2003/role/disclosureRef
-Topic 942
-SubTopic 210
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- Definition

Amount of financing receivable individually evaluated for credit loss. Excludes financing receivable collectively evaluated for credit loss.

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- Definition

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.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
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Allowance for Credit Losses - Schedule of Allowance for Credit Losses and Recorded Investment in Financing Receivables (Details) - USD ($) $ in Thousands	Aug. 31, 2026	May 31, 2026	Aug. 31, 2025	May 31, 2025
Allowance components:
Collective allowance	$ 33,779	$ 29,844
Asset-specific allowance	43	103
Total allowance for credit losses	33,822	29,947	$ 42,202	$ 40,615
Loans outstanding:
Collectively evaluated loans	38,309,656	38,392,544
Individually evaluated loans	8,002	10,871
Total	$ 38,317,658	$ 38,403,415	37,552,708
Financing receivable, allowance for coverage ratios	0.09%	0.08%
Deferred loan origination costs	$ 19,660		16,893
Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.09%	0.08%
Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.54%	0.95%
CFC:
Allowance components:
Collective allowance	$ 25,846	$ 24,153
Asset-specific allowance	43	103
Total allowance for credit losses	25,889	24,256	36,114	35,029
Loans outstanding:
Collectively evaluated loans	36,612,038	36,736,146
Individually evaluated loans	8,002	10,871
Total	$ 36,620,040	$ 36,747,017
Financing receivable, allowance for coverage ratios	0.07%	0.07%
Deferred loan origination costs	$ 20,000	$ 19,000
CFC: \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.07%	0.07%
CFC: \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.54%	0.95%
CFC: \| Distribution
Allowance components:
Collective allowance	$ 16,937	$ 16,625
Asset-specific allowance	0	0
Total allowance for credit losses	16,937	16,625	19,475	18,473
Loans outstanding:
Collectively evaluated loans	30,224,580	30,081,853
Individually evaluated loans	3,002	3,371
Total	$ 30,227,582	$ 30,085,224
Financing receivable, allowance for coverage ratios	0.06%	0.06%
CFC: \| Distribution \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.06%	0.06%
CFC: \| Distribution \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%	0.00%
CFC: \| Power supply
Allowance components:
Collective allowance	$ 7,924	$ 6,558
Asset-specific allowance	43	103
Total allowance for credit losses	7,967	6,661	15,551	15,456
Loans outstanding:
Collectively evaluated loans	6,123,758	6,395,896
Individually evaluated loans	5,000	7,500
Total	$ 6,128,758	$ 6,403,396
Financing receivable, allowance for coverage ratios	0.13%	0.10%
CFC: \| Power supply \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.13%	0.10%
CFC: \| Power supply \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.86%	1.37%
CFC: \| Statewide and associate
Allowance components:
Collective allowance	$ 985	$ 970
Asset-specific allowance	0	0
Total allowance for credit losses	985	970	1,088	1,100
Loans outstanding:
Collectively evaluated loans	263,700	258,397
Individually evaluated loans	0	0
Total	$ 263,700	$ 258,397
Financing receivable, allowance for coverage ratios	0.37%	0.38%
CFC: \| Statewide and associate \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.37%	0.38%
CFC: \| Statewide and associate \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%	0.00%
NCSC:
Allowance components:
Collective allowance	$ 7,933	$ 5,691
Asset-specific allowance	0	0
Total allowance for credit losses	7,933	5,691	6,088	5,586
Loans outstanding:
Collectively evaluated loans	1,697,618	1,656,398
Individually evaluated loans	0	0
Total	$ 1,697,618	$ 1,656,398
Financing receivable, allowance for coverage ratios	0.47%	0.34%
NCSC: \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.47%	0.34%
NCSC: \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%	0.00%
NCSC: \| Electric
Allowance components:
Collective allowance	$ 5,836	$ 4,108
Asset-specific allowance	0	0
Total allowance for credit losses	5,836	4,108	4,290	3,818
Loans outstanding:
Collectively evaluated loans	1,111,967	1,073,794
Individually evaluated loans	0	0
Total	$ 1,111,967	$ 1,073,794
Financing receivable, allowance for coverage ratios	0.52%	0.38%
NCSC: \| Electric \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.52%	0.38%
NCSC: \| Electric \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%	0.00%
NCSC: \| Telecom
Allowance components:
Collective allowance	$ 2,097	$ 1,583
Asset-specific allowance	0	0
Total allowance for credit losses	2,097	1,583	$ 1,798	$ 1,768
Loans outstanding:
Collectively evaluated loans	585,651	582,604
Individually evaluated loans	0	0
Total	$ 585,651	$ 582,604
Financing receivable, allowance for coverage ratios	0.36%	0.27%
NCSC: \| Telecom \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.36%	0.27%
NCSC: \| Telecom \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%	0.00%