Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 67,228	$ 81,813
Accumulated depreciation and amortization	$ 745,761	$ 745,397
Common stock, no par value	$ 0	$ 0
Common stock, stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	238,336,760	246,198,878
Treasury shares	36,377,441	36,944,789

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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