Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Equity method investment	$ 37,074		$ 37,074		$ 28,593
Equity in earnings of equity method investments	$ 1,329	$ 2,530	$ 4,931	$ 7,249
ULVAC Cryogenics, Inc.
Schedule of Equity Method Investments [Line Items]
Joint venture interest (as a percent)	50.00%		50.00%
Equity method investment	$ 37,100		$ 37,100		$ 28,600
Equity in earnings of equity method investments	1,300	2,500	4,900	7,700
Management fee payments received	$ 300	$ 300	$ 800	$ 800