Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Apr. 30, 2015	Apr. 30, 2014
Allowance for doubtful accounts	$ 10	$ 9
Unamortized discount	$ 2	$ 3
Treasury stock, shares	18,613,000us-gaap_TreasuryStockShares	13,858,000us-gaap_TreasuryStockShares
Common stock, Class A, voting [Member]
Common stock, par value	$ 0.15	$ 0.15
Common stock, shares authorized	85,000,000	85,000,000
Common stock, shares issued	85,000,000	85,000,000
Common Stock, Class B, nonvoting [Member]
Common stock, par value	$ 0.15	$ 0.15
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	142,313,000	142,313,000

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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