Restructuring And Related Costs (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Oct. 01, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 2,730,000	$ 4,079,000	$ 2,165,000
2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred to date		4,741,000
2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		0	0
2016 Restructuring Plan [Member] | Machida, Japan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred to date		1,964,000
2014 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		0	$ 0	0
Employee Severance [Member] | 2018 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		880,000
Employee Severance [Member] | 2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 2,899,000	1,550,000
Restructuring and related cost, incurred to date		4,449,000
Employee Severance [Member] | 2017 Restructuring Plan [Member] | Machida, Japan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense		31,000
Restructuring and related cost, incurred to date		152,000
Employee Severance [Member] | 2016 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense				$ 1,237,000
Employee Severance [Member] | 2016 Restructuring Plan [Member] | Machida, Japan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred to date		1,444,000
Facility Closing [Member] | 2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 23,000	269,000
Restructuring and related cost, incurred to date		292,000
Facility Closing [Member] | 2016 Restructuring Plan [Member] | Machida, Japan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred to date		520,000
2019 [Member] | 2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost remaining		150,000
2019 [Member] | Employee Severance [Member] | 2017 Restructuring Plan [Member] | Machida, Japan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost remaining		$ 15,000