Revenue (Narrative) (Details) $ in Thousands	6 Months Ended
	Mar. 30, 2019 reporting_unit	Sep. 30, 2018 USD ($)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect of new accounting principle in period of adoption		$ (6,227)
Number of reportable segments | reporting_unit	2
Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect of new accounting principle in period of adoption		$ (6,227)
Minimum | Sensors
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating cycle	1 month
Maximum | Test & Simulation
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating cycle	12 months
Maximum | Sensors
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Operating cycle	3 months