Income Taxes - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018
Income before income taxes:
United States	$ 209,443	$ 185,535	$ 180,034
Foreign	18,548	(10,399)	(5,472)
Total income before income taxes	227,991	175,136	174,562
Current:
Federal	24,102	30,051	46,840
State	6,872	8,923	9,228
Foreign	20,398	15,016	10,897
Total current income tax expense	51,372	53,990	66,965
Deferred:
Federal	2,187	(9,108)	(22,072)
State	870	(1,195)	(1,471)
Foreign	(328)	(27,312)	(5,817)
Total deferred income tax expense	2,729	(37,615)	(29,360)
Total income tax expense	$ 54,101	$ 16,375	$ 37,605
Reconciliation of effective income tax rate
Tax at federal statutory rate	21.00%	21.00%	24.50%
State taxes, net of federal benefit	2.70%	3.40%	4.20%
Research and Development ("R&D") credits	(2.20%)	(4.70%)	(1.40%)
Domestic production deduction	0.00%	0.00%	(0.20%)
Tax differential on foreign earnings	0.70%	1.00%	0.50%
Non-taxable foreign interest income	(1.10%)	(1.70%)	(2.00%)
Goodwill	1.50%	0.90%	1.70%
Stock compensation	(2.20%)	(2.40%)	(2.70%)
Valuation allowance	1.60%	(13.50%)	(0.50%)
Change in uncertain tax positions	0.40%	2.40%	1.90%
Revaluation of deferred taxes	0	(0.014)	(0.084)
Deferred tax adjustments	(1.30%)	(0.40%)	2.10%
Transition tax on foreign earnings	0	0.014	0
Other	2.60%	3.30%	1.80%
Total income tax expense	23.70%	9.30%	21.50%