Leases - Supplemental Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Sep. 26, 2020	Mar. 28, 2020
Operating leases
Operating lease right-of-use assets	$ 135,552	$ 115,882	$ 99,098
Current lease liabilities	40,586	33,495	32,403
Non-current lease liabilities	99,840	$ 86,516	70,760
Total operating lease liabilities	140,400		103,200
Finance leases
Finance lease right-of-use assets	300		400
Current lease liabilities	100		100
Non-current lease liabilities	0		100
Total finance lease liabilities	$ 100		$ 200
Weighted-average remaining lease term (in years):
Operating leases	4 years 7 months 6 days		4 years 9 months 18 days
Finance leases	1 year 6 months		2 years 4 months 24 days
Weighted-average discount rate:
Operating leases	2.80%		3.80%
Finance leases	4.80%		4.90%
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet		us-gaap:PropertyPlantAndEquipmentNet
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtCurrent		us-gaap:LongTermDebtCurrent
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt		Long-term debt