Intangible Assets (Narrative) (Details) - USD ($) $ in Millions			12 Months Ended
	Jan. 30, 2015	Dec. 24, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Business Acquisition [Line Items]
Amortization of intangible assets			$ 0.8	$ 0.8	$ 1.2
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization in fiscal year 2018			0.6
Amortization in fiscal year 2019			0.6
Amortization in fiscal year 2020			0.6
Amortization in fiscal year 2021			0.4
Amortization in fiscal year 2022			0.3
Amortization thereafter			$ 1.2
SoLayTec, B.V.
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Percentage of voting interests acquired		51.00%
Intangible assets acquired		$ 2.1
BTU International, Inc (BTU)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Intangible assets acquired	$ 2.9
Technology | SoLayTec, B.V.
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Intangible assets acquired		1.9
Trade names | SoLayTec, B.V.
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Intangible assets acquired		$ 0.2
Trade names | BTU International, Inc (BTU)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Intangible assets acquired	1.2
Customer lists | BTU International, Inc (BTU)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Intangible assets acquired	$ 1.7
Kingstone Holding Company
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Intangible assets derecognized					3.2
Accumulated amortization derecognized					$ 1.9