Loans - Schedule of analysis of the age of the recorded investment in loans outstanding by member class (Details) - USD ($) $ in Thousands	May 31, 2026	May 31, 2025
Payment Status of Loans
Total loans outstanding	$ 38,403,415	$ 37,063,548
Nonaccrual Loans	$ 7,500	$ 26,099
As a % of total loans
Current, Percentage of total loans	100.00%	100.00%
30-89 days past due, Percentage of total loans	0.00%	0.00%
> 90 days past due, Percentage of total loans	0.00%	0.00%
Total past due, Percentage of total loans	0.00%	0.00%
Total loans outstanding, Percentage of total loans	100.00%	100.00%
Nonaccrual loans, Percentage of total loans	0.02%	0.07%
CFC
Payment Status of Loans
Total loans outstanding	$ 36,747,017	$ 35,409,320
Nonaccrual Loans	7,500	26,099
CFC | Distribution
Payment Status of Loans
Total loans outstanding	30,085,224	29,262,495
Nonaccrual Loans	0	0
CFC | Power supply
Payment Status of Loans
Total loans outstanding	6,403,396	5,895,500
Nonaccrual Loans	7,500	26,099
CFC | Statewide and associate
Payment Status of Loans
Total loans outstanding	258,397	251,325
Nonaccrual Loans	0	0
NCSC
Payment Status of Loans
Total loans outstanding	1,656,398	1,654,228
Nonaccrual Loans	0	0
NCSC | Electric
Payment Status of Loans
Total loans outstanding	1,073,794	1,078,763
Nonaccrual Loans	0	0
NCSC | Telecom
Payment Status of Loans
Total loans outstanding	582,604	575,465
Nonaccrual Loans	0	0
Current
Payment Status of Loans
Total loans outstanding	38,403,415	37,063,548
Current | CFC
Payment Status of Loans
Total loans outstanding	36,747,017	35,409,320
Current | CFC | Distribution
Payment Status of Loans
Total loans outstanding	30,085,224	29,262,495
Current | CFC | Power supply
Payment Status of Loans
Total loans outstanding	6,403,396	5,895,500
Current | CFC | Statewide and associate
Payment Status of Loans
Total loans outstanding	258,397	251,325
Current | NCSC
Payment Status of Loans
Total loans outstanding	1,656,398	1,654,228
Current | NCSC | Electric
Payment Status of Loans
Total loans outstanding	1,073,794	1,078,763
Current | NCSC | Telecom
Payment Status of Loans
Total loans outstanding	582,604	575,465
Total Past Due
Payment Status of Loans
Total loans outstanding	0	0
Total Past Due | CFC
Payment Status of Loans
Total loans outstanding	0	0
Total Past Due | CFC | Distribution
Payment Status of Loans
Total loans outstanding	0	0
Total Past Due | CFC | Power supply
Payment Status of Loans
Total loans outstanding	0	0
Total Past Due | CFC | Statewide and associate
Payment Status of Loans
Total loans outstanding	0	0
Total Past Due | NCSC
Payment Status of Loans
Total loans outstanding	0	0
Total Past Due | NCSC | Electric
Payment Status of Loans
Total loans outstanding	0	0
Total Past Due | NCSC | Telecom
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due | CFC
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due | CFC | Distribution
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due | CFC | Power supply
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due | CFC | Statewide and associate
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due | NCSC
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due | NCSC | Electric
Payment Status of Loans
Total loans outstanding	0	0
30-89 Days Past Due | NCSC | Telecom
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due | CFC
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due | CFC | Distribution
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due | CFC | Power supply
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due | CFC | Statewide and associate
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due | NCSC
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due | NCSC | Electric
Payment Status of Loans
Total loans outstanding	0	0
> 90 Days Past Due | NCSC | Telecom
Payment Status of Loans
Total loans outstanding	$ 0	$ 0