Equity Method and Other Investments - ULVAC Cryogenics, Inc. (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 28,593	$ 27,273
Equity in earnings (losses) of equity method investments	$ 9,381	2,380	$ (164)
Ulvac Cryogenics Incorporated
Schedule of Equity Method Investments [Line Items]
Joint venture interest (as a percent)	50.00%
Equity method investments	$ 28,600	25,600
Equity in earnings (losses) of equity method investments	9,800	3,400	1,400
Management fee payments received	1,100	800	600
Charges incurred from related parties	300	300	$ 400
Accounts payable for unpaid products and services	100	100
Cash dividend received	$ 5,400	$ 1,500