XML 40 R28.htm IDEA: XBRL DOCUMENT v3.19.1
Inventories - Narrative (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2019
Mar. 31, 2018
Sep. 30, 2018
Inventory Disclosure [Abstract]          
Percentage of inventories determined using LIFO method 27.00%   27.00%   54.00%
Additional amount that would have been reported in inventory if FIFO method had been used $ 8,314   $ 8,314   $ 8,879
Inventory [Line Items]          
Cost of goods sold $ (25,304) $ (25,265) (51,633) $ (47,487)  
Accounting Standards Update 2014-09          
Inventory [Line Items]          
Cost of goods sold     $ 333