Derivative Instruments and Hedging Activities - Schedule of Derivatives Offsetting (Details) - USD ($) $ in Thousands	Feb. 28, 2026	May 31, 2025
Derivative [Line Items]
Derivative asset, fair value, amount not offset against collateral	$ 418,984	$ 555,855
Derivative liability, fair value, amount not offset against collateral	48,156	51,368
Interest rate swaps
Derivative [Line Items]
Derivative asset, fair value, gross asset	418,984	555,855
Derivative asset, fair value, gross liability	0	0
Derivative asset, fair value, amount not offset against collateral	418,984	555,855
Derivative, collateral, obligation to return securities	46,657	49,806
Derivative, collateral, obligation to return cash	0	0
Derivative asset, fair value, amount offset against collateral	372,327	506,049
Derivative liability, fair value, gross liability	48,156	51,368
Derivative liability, fair value, gross asset	0	0
Derivative liability, fair value, amount not offset against collateral	48,156	51,368
Derivative, collateral, right to reclaim securities	46,657	49,806
Derivative, collateral, right to reclaim cash	0	0
Derivative liability, fair value, amount offset against collateral	$ 1,499	$ 1,562