Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jul. 31, 2018	Apr. 30, 2018
Condensed Consolidated Balance Sheets
Trade accounts and notes receivable, allowances (in dollars)	$ 7,982	$ 9,633
Property and equipment, accumulated depreciation (in dollars)	$ 94,015	$ 85,761
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	500,000	500,000
Common stock, shares issued	41,139	41,069
Common stock, shares outstanding	41,139	41,069
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000	50,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0