Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	May 31, 2019	May 31, 2018
Statement Of Financial Position [Abstract]
Receivables, allowances	$ 1,150	$ 632
Other intangible assets, accumulated amortization	$ 87,759	$ 74,922
Preferred shares, without par value
Preferred shares, shares authorized	1,000,000	1,000,000
Preferred shares, shares issued	0	0
Preferred shares, shares outstanding	0	0
Common stock, without par value
Common shares, authorized	150,000,000	150,000,000
Common shares, shares issued	55,467,525	58,876,921
Common shares, shares outstanding	55,467,525	58,876,921
Accumulated other comprehensive income (loss), taxes	$ 7,100	$ 2,908