Income Taxes - Reconciliation Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2018	May 31, 2017
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of period	$ 17,357	$ 16,531
Additions from G&K acquisition	6,394	2,084
Additions for tax positions of prior years	5,675	2,520
Settlements		(1,044)
Statute expirations	(2,943)	(2,734)
Additions for tax positions of the current year	10,164
Balance at end of period	$ 36,647	$ 17,357