Equity Method Investments ULVAC Cryogenics, Inc. (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 29,803		$ 29,803		$ 27,273
Equity in earnings of equity method investments	$ 2,777	$ 710	$ 4,719	$ 869
ULVAC Cryogenics, Inc.
Schedule of Equity Method Investments [Line Items]
Joint venture interest, percentage	50.00%		50.00%
Equity method investments	$ 29,800		$ 29,800		25,600
Equity in earnings of equity method investments	2,800	800	5,200	1,300
Management fee payments received	200	200	500	400
Charges incurred from related parties		$ 100		$ 200
Accounts payable for unpaid products and services (less than)	$ 100		$ 100		$ 100