Derivative Notional Amounts and Weighted-Average Rate (Details) - USD ($) $ in Thousands	Nov. 30, 2019	May 31, 2019
Derivative [Line Items]
Derivative, Notional Amount	$ 10,435,741	$ 10,843,280
Pay-fixed swaps
Derivative [Line Items]
Derivative, Notional Amount	$ 7,271,741	$ 7,379,280
Derivative, Average Fixed Interest Rate	2.84%	2.83%
Derivative, Average Variable Interest Rate	2.00%	2.60%
Receive fixed swaps
Derivative [Line Items]
Derivative, Notional Amount	$ 3,099,000	$ 3,399,000
Derivative, Average Fixed Interest Rate	2.66%	2.56%
Derivative, Average Variable Interest Rate	2.66%	3.25%
Interest Rate Swap
Derivative [Line Items]
Derivative, Notional Amount	$ 10,370,741	$ 10,778,280
Derivative Weighted Average Interest Rate Paid Percentage	2.78%	2.97%
Derivative Weighted Average Interest Rate Received Percentage	2.20%	2.58%
Forward Contracts
Derivative [Line Items]
Derivative, Notional Amount	$ 65,000	$ 65,000