Inventories - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015
Inventory Disclosure [Abstract]
Percentage of inventories determined using LIFO method	39.00%	38.00%
Difference between cost of inventories if FIFO method had been used	$ 8,542	$ 8,508

Amount of difference between inventory at lower of LIFO cost or market and inventory at lower of other inventory accounting method cost or market, for example, but not limited to, FIFO or average cost.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(c))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_InventoryLIFOReserve
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant