Restructuring and Related Costs (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 362	$ 381	$ 608	$ 944
2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	3,523		3,523
2014 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	0	0
Machida, Japan | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	$ 381	0	$ 944
Cost incurred to date	1,964		1,964
Employee Severance | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	321		414
Cost incurred to date	3,313		3,313
Employee Severance | Machida, Japan | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	16		7
Cost incurred to date	137		137
Expected cost remaining	60		60
Employee Severance | Machida, Japan | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	1,444		1,444
Facility Closing | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	25		187
Cost incurred to date	210		210
Facility Closing | Machida, Japan | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Cost incurred to date	520		520
Minimum | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	1,000		1,000
Maximum | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	$ 2,000		$ 2,000