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

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- Definition

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
-Paragraph a
-Subparagraph (1)
-Publisher SEC

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- References

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- Definition

Amount excluding accrued interest, of allowance for credit loss on 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
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.5.a)
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-SubTopic 20
-Name Accounting Standards Codification
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-Paragraph 2
-Publisher FASB
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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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- 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
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

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- Definition

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

+ References

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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.

+ References

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

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Allowance for Credit Losses - Schedule of Allowance for Credit Losses and Recorded Investment in Financing Receivables (Details) - USD ($) $ in Thousands	Feb. 28, 2026	Nov. 30, 2025	May 31, 2025	Feb. 28, 2025	Nov. 30, 2024	May 31, 2024
Allowance components:
Collective allowance	$ 35,515		$ 31,313
Asset-specific allowance	197		9,302
Total allowance for credit losses	35,712	$ 43,423	40,615	$ 44,456	$ 50,549	$ 48,726
Loans outstanding:
Collectively evaluated loans	38,715,421		37,031,238
Individually evaluated loans	16,258		32,310
Total	$ 38,731,679		$ 37,063,548	36,463,440
Financing receivable, allowance for coverage ratios	0.09%		0.11%
Deferred loan origination costs	$ 18,203			15,769
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	1.21%		28.79%
CFC:
Allowance components:
Collective allowance	$ 28,263		$ 25,773
Asset-specific allowance	197		9,256
Total allowance for credit losses	28,460	36,808	35,029	37,663	44,032	42,726
Loans outstanding:
Collectively evaluated loans	36,933,042		35,379,467
Individually evaluated loans	16,258		29,853
Total	$ 36,949,300		$ 35,409,320
Financing receivable, allowance for coverage ratios	0.08%		0.10%
Deferred loan origination costs	$ 18,000		$ 16,000
CFC: \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.08%		0.07%
CFC: \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	1.21%		31.01%
CFC: \| Distribution
Allowance components:
Collective allowance	$ 20,376		$ 18,473
Asset-specific allowance	0		0
Total allowance for credit losses	20,376	20,102	18,473	19,501	18,049	15,954
Loans outstanding:
Collectively evaluated loans	30,383,915		29,258,741
Individually evaluated loans	3,371		3,754
Total	$ 30,387,286		$ 29,262,495
Financing receivable, allowance for coverage ratios	0.07%		0.06%
CFC: \| Distribution \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.07%		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	$ 6,818		$ 6,200
Asset-specific allowance	197		9,256
Total allowance for credit losses	7,015	15,593	15,456	16,995	24,785	25,583
Loans outstanding:
Collectively evaluated loans	6,275,950		5,869,401
Individually evaluated loans	12,887		26,099
Total	$ 6,288,837		$ 5,895,500
Financing receivable, allowance for coverage ratios	0.11%		0.26%
CFC: \| Power supply \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.11%		0.11%
CFC: \| Power supply \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	1.53%		35.46%
CFC: \| Statewide and associate
Allowance components:
Collective allowance	$ 1,069		$ 1,100
Asset-specific allowance	0		0
Total allowance for credit losses	1,069	1,113	1,100	1,167	1,198	1,189
Loans outstanding:
Collectively evaluated loans	273,177		251,325
Individually evaluated loans	0		0
Total	$ 273,177		$ 251,325
Financing receivable, allowance for coverage ratios	0.39%		0.44%
CFC: \| Statewide and associate \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.39%		0.44%
CFC: \| Statewide and associate \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%		0.00%
NCSC:
Allowance components:
Collective allowance	$ 7,252		$ 5,540
Asset-specific allowance	0		46
Total allowance for credit losses	7,252	6,615	5,586	6,793	6,517	6,000
Loans outstanding:
Collectively evaluated loans	1,782,379		1,651,771
Individually evaluated loans	0		2,457
Total	$ 1,782,379		$ 1,654,228
Financing receivable, allowance for coverage ratios	0.41%		0.34%
NCSC: \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.41%		0.34%
NCSC: \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%		1.87%
NCSC: \| Electric
Allowance components:
Collective allowance	$ 5,202		$ 3,818
Asset-specific allowance	0		0
Total allowance for credit losses	5,202	4,576	3,818	4,381	4,091	3,937
Loans outstanding:
Collectively evaluated loans	1,163,391		1,078,763
Individually evaluated loans	0		0
Total	$ 1,163,391		$ 1,078,763
Financing receivable, allowance for coverage ratios	0.45%		0.35%
NCSC: \| Electric \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.45%		0.35%
NCSC: \| Electric \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%		0.00%
NCSC: \| Telecom
Allowance components:
Collective allowance	$ 2,050		$ 1,722
Asset-specific allowance	0		46
Total allowance for credit losses	2,050	$ 2,039	1,768	$ 2,412	$ 2,426	$ 2,063
Loans outstanding:
Collectively evaluated loans	618,988		573,008
Individually evaluated loans	0		2,457
Total	$ 618,988		$ 575,465
Financing receivable, allowance for coverage ratios	0.33%		0.31%
NCSC: \| Telecom \| Collective Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.33%		0.30%
NCSC: \| Telecom \| Asset-Specific Allowance
Loans outstanding:
Financing receivable, allowance for coverage ratios	0.00%		1.87%