Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 29, 2019	Dec. 29, 2018	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Income Taxes [Line Items]
U.S. federal statutory income tax rate			21.00%	24.50%	35.00%
Discrete tax benefit		$ 1,293,000	$ 3,547,000	$ 25,008,000	$ 2,801,000
Effective income tax rate reconciliation, change in enacted tax rate, amount		(1,297,000)		$ 31,647,000
Tax Cuts and Jobs Act of 2017, other measurement period adjustment, income tax expense (benefit)		$ 4,000
Tax Cuts And Jobs Act Of 2017, potential future income tax expense (benefit)	$ 1,297,000
Effective income tax rate			11.40%	(38.70%)	(9.00%)
Effective income tax rate, percent excluding certain discrete tax benefits			18.70%	17.90%	3.20%
Deferred tax asset, provisional income tax expense (benefit)				$ 6,639,000
R&D tax credit carryover			$ 3,774,000	3,337,000
Foreign earnings repatriated			5,943,000	54,778,000
Effective income tax rate reconciliation, repatriation of foreign earnings, amount			437,000
Foreign undistributed earnings			68,784,000	73,819,000
Unrecognized tax benefits that would affect the effective tax rate			2,761,000	3,740,000
Accrued interest related to uncertain income tax positions			332,000	542,000
Accrual for penalties related to uncertain tax positions			0	0
Current income tax receivable			4,282,000	5,155,000
Minnesota (R&D)
Income Taxes [Line Items]
R&D tax credit carryover			$ 3,768,000
R&D carryforward period			15 years
New York and North Carolina
Income Taxes [Line Items]
Tax credit carryforwards			$ 1,224,000
Germany and Japan
Income Taxes [Line Items]
Foreign earnings repatriated					$ 15,272,000
Effective income tax rate reconciliation, repatriation of foreign earnings, amount				$ 1,249,000	$ 11,000