Consolidated balance sheets (Parenthetical) - $ / shares
May. 30, 2015
Feb. 28, 2015
May. 31, 2014
Consolidated balance sheets      
Common stock, par value (in dollars per share) $ 0.01 $ 0.01 $ 0.01
Common stock, shares authorized 250,000,000 250,000,000 250,000,000
Common stock, shares issued 47,983,804 47,983,660 47,974,829
Common stock, shares outstanding 47,983,804 47,983,660 47,974,829