Restructuring and Separation Expenses (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($) facility
Restructuring Cost and Reserve [Line Items]
Restructuring and separation costs incurred		$ 1,322	$ 8,441	$ 3,397
Restructuring and separation costs paid		1,000	6,800
Restructuring and separation costs payable over the next fiscal year		$ 300
Separation costs	$ 3,800		7,900
Restructuring costs related to exited of Canadian facility lease and write-off of associated leasehold improvements			500	$ 800
Number of previously occupied leased facilities | facility				1
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and separation costs incurred				$ 2,600
Restructuring and separation costs payable over the next fiscal year			$ 1,100