Inventories - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 29, 2016
Inventory Disclosure [Abstract]
Excess of current costs at FIFO over LIFO stated values	$ 4.9	$ 4.7
Decrease in cost of sales	$ 0.3	$ 0.2	$ 0.0