Income Taxes - Reconciliation Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2021	May 31, 2020
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of period	$ 44,670	$ 48,715
Additions for tax positions of the current year	4,728	3,976
Additions for tax positions of prior years	2,726	4,325
Settlements	(5,593)	(5,473)
Statute expirations	(4,074)	(6,873)
Balance at end of period	$ 42,457	$ 44,670