Restructuring Expenses - Additional Information (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($) Employee	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($) Employee
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0	$ 4,500,000	$ 0	$ 4,500,000
Number of positions eliminated | Employee		79		79
Facilities charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 1,700,000		$ 1,700,000
Employee separation
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 2,800,000		$ 2,800,000