Consolidated Balance Sheets (Parenthetical) - $ / shares	Aug. 31, 2017	Aug. 31, 2016
Preferred stock, without par value
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, outstanding
Common stock, without par value
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares outstanding	28,503,000	28,205,000