Inventories - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Jun. 30, 2016	Jun. 30, 2016
Three to Four Years Old Inventory [Member]
Inventory [Line Items]
Cost basis reduction in inventory, percentage		50.00%
Inventory, minimum time period on the shelf, years		3 years
Inventory, maximum time period on the shelf, years		4 years
Four to Five Years Old Inventory [Member]
Inventory [Line Items]
Cost basis reduction in inventory, percentage		75.00%
Inventory, minimum time period on the shelf, years		4 years
Inventory, maximum time period on the shelf, years		5 years
Greater Than Five Years Old Inventory [Member]
Inventory [Line Items]
Inventory, minimum time period on the shelf, years		5 years
Inventory valuation estimate		$ 0
Provisions on obsolescence	$ 0	$ 0