Income Taxes - Tax Jurisdictions and Years Currently under Audit Exam (Details)	9 Months Ended
	Jun. 30, 2020
BELGIUM
Income Tax Examination [Line Items]
Tax years currently under audit exam	2015 2016 2017 2018 2019
Germany
Income Tax Examination [Line Items]
Tax years currently under audit exam	2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
TAIWAN, PROVINCE OF CHINA
Income Tax Examination [Line Items]
Tax years currently under audit exam	2017 2018
United Kingdom
Income Tax Examination [Line Items]
Tax years currently under audit exam	2014 2015 2017