Guarantees Outstanding (Details) - USD ($) $ in Thousands		Nov. 30, 2019	May 31, 2019
Guarantees
Guarantor obligations		$ 794,723	$ 837,435
CFC
Guarantees
Guarantor obligations		782,132	827,344
CFC | Distribution
Guarantees
Guarantor obligations		243,668	235,919
CFC | Power supply
Guarantees
Guarantor obligations		533,168	586,717
CFC | Statewide and associate
Guarantees
Guarantor obligations		5,296	4,708
NCSC
Guarantees
Guarantor obligations		12,591	8,517
RTFC
Guarantees
Guarantor obligations		0	1,574
Long-term tax-exempt bonds
Guarantees
Guarantor obligations	[1]	308,750	312,190
Letters of credit
Guarantees
Guarantor obligations	[2]	339,241	379,001
Other guarantees
Guarantees
Guarantor obligations		$ 146,732	$ 146,244

[1] Represents the outstanding principal amount of long-term fixed-rate and variable-rate guaranteed bonds.

[2] Reflects our maximum potential exposure for letters of credit.