Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	May 31, 2012	May 31, 2011
Receivables, allowances	$ 3,329	$ 4,150
Other intangible assets, accumulated amortization	16,103	12,688
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	67,906,369	71,683,876
Common shares, shares outstanding	67,906,369	71,683,876
Accumulated other comprehensive income (loss), taxes	$ 10,749	$ 5,456