Restructuring and Related Costs (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 246	$ 563
2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	3,177
2014 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0
Machida, Japan | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	563
Cost incurred to date	1,964
Employee Severance | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	93
Cost incurred to date	2,992
Employee Severance | Machida, Japan | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	112
Employee Severance | Machida, Japan | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	1,444
Facility Closing | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	162
Cost incurred to date	185
Facility Closing | Machida, Japan | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	520
Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(9)	$ 563
Sensors | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(9)
2018 | Employee Severance | Machida, Japan | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Expected cost remaining	74
Minimum | 2018 | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Expected cost remaining	1,000
Maximum | 2018 | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Expected cost remaining	$ 3,000