Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Oct. 01, 2016
Income Taxes [Line Items]
U.S. federal statutory income tax rate	24.50%	35.00%	35.00%
Discrete tax benefit	$ 25,008,000	$ 2,801,000	$ 2,283,000
Effective income tax rate reconciliation, change in enacted tax rate, amount	31,647,000
Deferred tax asset, provisional income tax expense (benefit)	6,639,000
Deferred tax liability, provisional income tax benefit	32,244,000
Tax Cuts and Jobs Act of 2017, provisional income tax expense (benefit)	$ (597,000)
Effective income tax rate	(38.70%)	(9.00%)	18.00%
Effective income tax rate, percent excluding certain discrete tax benefits	17.90%	3.20%	19.30%
Nondeductible PCB acquisition-related expense			$ 1,834,000
R&D tax credit carryover	$ 3,337,000	$ 2,231,000
Foreign Earnings Repatriated	54,778,000
Effective income tax rate reconciliation, repatriation of foreign earnings, amount	1,249,000
Foreign undistributed earnings	73,819,000	111,717,000
Unrecognized tax benefits that would affect the effective tax rate	3,740,000	3,234,000
Accrued interest related to uncertain income tax positions	542,000	404,000
Accrual for penalties related to uncertain tax positions	0	0
Current income tax receivable	5,155,000	5,392,000
Minnesota (R&D) [Member]
Income Taxes [Line Items]
R&D tax credit carryover	$ 3,337,000
R&D carryforward period	15 years
Germany And Japan [Member]
Income Taxes [Line Items]
Foreign Earnings Repatriated		15,272,000	10,324,000
Effective income tax rate reconciliation, repatriation of foreign earnings, amount		$ 11,000	$ 112,000