Derivative Instruments and Hedging Activities - Derivatives Offsetting (Details) - USD ($) $ in Thousands	Aug. 31, 2023	May 31, 2023
Derivative [Line Items]
Derivative asset, fair value, amount not offset against collateral	$ 615,866	$ 460,762
Derivative liability, fair value, amount not offset against collateral	108,239	115,074
Interest rate swaps
Derivative [Line Items]
Derivative asset, fair value, gross asset	615,866	460,762
Derivative asset, fair value, gross liability	0	0
Derivative asset, fair value, amount not offset against collateral	615,866	460,762
Derivative, collateral, obligation to return securities	106,557	112,047
Derivative, collateral, obligation to return cash	0	0
Derivative asset, fair value, amount offset against collateral	509,309	348,715
Derivative liability, fair value, gross liability	108,239	115,074
Derivative liability, fair value, gross asset	0	0
Derivative liability, fair value, amount not offset against collateral	108,239	115,074
Derivative, collateral, right to reclaim securities	106,557	112,047
Derivative, collateral, right to reclaim cash	0	0
Derivative liability, fair value, amount offset against collateral	$ 1,682	$ 3,027