Members' Subordinated Certificates - Narrative (Details)	12 Months Ended
	May 31, 2023	May 31, 2022
Membership subordinated certificates
Members' subordinated certificates
Maturity period	100 years
Interest rate	5.00%
Member capital security, call option term	5 years	10 years
Securities maturing through 2052
Members' subordinated certificates
Maturity period	30 years
Weighted average | Membership subordinated certificates
Members' subordinated certificates
Maturity period	54 years	55 years