CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Oct. 31, 2017	Apr. 30, 2017
Allowance for doubtful accounts	$ 15,930	$ 15,455
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	71,529,000	70,811,000
Common stock, shares outstanding	56,511,000	56,938,000