Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Feb. 28, 2015	May 31, 2014
Receivables, allowance	$ 4,190	$ 4,784
Intangible assets, accumulated amortization	$ 15,058	$ 12,698
Preferred stock, shares authorized	500,000us-gaap_PreferredStockSharesAuthorized	500,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued
Common stock, par value	$ 0.30	$ 0.30
Common stock, shares authorized	60,000,000us-gaap_CommonStockSharesAuthorized	60,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	20,788,784us-gaap_CommonStockSharesIssued	20,477,938us-gaap_CommonStockSharesIssued
Treasury stock at cost, shares	546,977us-gaap_TreasuryStockShares	0us-gaap_TreasuryStockShares

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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