Interest Income and Interest Expense - Schedule of interest income and expense (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2026	May 31, 2025	May 31, 2024
Interest income:
Cash, time deposits and investment securities	$ 5,925	$ 11,890	$ 26,902
Interest income	1,796,660	1,703,233	1,593,351
Interest expense
Short-term borrowings	189,657	189,429	250,316
Total interest expense	1,494,894	1,442,279	1,339,088
Net interest income	301,766	260,954	254,263
Loans
Interest income:
Loans	1,790,735	1,691,343	1,566,449
Long-term debt
Interest expense
Debt	1,173,995	1,113,480	952,659
Subordinated debt
Interest expense
Debt	$ 131,242	$ 139,370	$ 136,113