Other Balance Sheet Information - Summary of Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials and purchased parts	$ 79,633	$ 73,819
Work-in-process	17,503	10,548
Finished goods	29,458	22,028
Inventory, net	126,594	106,395
Reserves for excess and obsolete inventory	$ 21,500	$ 23,500