Short-Term Borrowings - Outstanding (Details) - USD ($) $ in Thousands	Nov. 30, 2019		May 31, 2019
Short-term Debt [Line Items]
Short-term borrowings	$ 4,789,024		$ 3,607,726
Commercial paper sold through dealers, net of discounts
Short-term Debt [Line Items]
Short-term borrowings	1,038,862		944,616
Commercial paper sold directly to members, at par
Short-term Debt [Line Items]
Short-term borrowings	1,371,902		1,111,795
Commercial paper
Short-term Debt [Line Items]
Short-term borrowings	2,410,764		2,056,411
Select notes to members
Short-term Debt [Line Items]
Short-term borrowings	1,470,579		1,023,952
Daily liquidity fund notes to members
Short-term Debt [Line Items]
Short-term borrowings	508,169		298,817
Medium-term notes sold to members
Short-term Debt [Line Items]
Short-term borrowings	249,512		228,546
Farmer Mac notes payable
Short-term Debt [Line Items]
Short-term borrowings	$ 150,000	[1]	$ 0

[1] Facility fee determined by CFC’s senior unsecured credit ratings based on the pricing schedules put in place at the inception of the related agreement.