Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Feb. 28, 2015	May 31, 2014
Trade accounts receivable, allowances	$ 25,975	$ 27,641
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized	50,000,000us-gaap_PreferredStockSharesAuthorized	50,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	300,000,000us-gaap_CommonStockSharesAuthorized	300,000,000us-gaap_CommonStockSharesAuthorized
Common stock, issued	138,788,000us-gaap_CommonStockSharesIssued	138,039,000us-gaap_CommonStockSharesIssued
Common stock, outstanding	133,236,000us-gaap_CommonStockSharesOutstanding	133,273,000us-gaap_CommonStockSharesOutstanding

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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