Interest Income and Interest Expense - Schedule of Interest Income and Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2021	Nov. 30, 2020	Nov. 30, 2021	Nov. 30, 2020
Interest income:
Investment securities	$ 3,784	$ 3,857	$ 8,233	$ 7,743
Interest income	283,152	276,499	566,420	556,083
Interest expense:
Short-term borrowings	3,076	3,403	6,469	7,744
Total interest expense	173,596	174,422	348,373	354,398
Net interest income	109,556	102,077	218,047	201,685
Loans receivable
Interest income:
Loans	279,368	272,642	558,187	548,340
Long-term debt
Interest expense:
Long-term debt and subordinated debt	144,096	144,579	288,969	293,492
Subordinated debt
Interest expense:
Long-term debt and subordinated debt	$ 26,424	$ 26,440	$ 52,935	$ 53,162