Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 526,709	$ 477,921
Work-in-process	89,437	86,367
Finished goods	85,520	90,354
Total inventories	$ 701,666	$ 654,642