Leases - Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 26, 2020	Sep. 30, 2019
Operating And Finance Lease, Right-of-Use Assets [Abstract]
Operating lease assets	$ 37,068
Finance lease assets	3,570
Total right-of-use assets, gross	40,638
Less: accumulated depreciation	(1,956)
Right-of-use assets, net	38,682	$ 0
Current liabilities:
Current portion of operating lease liabilities	11,207
Current portion of finance lease liabilities	358
Lease obligations	11,565	0
Noncurrent liabilities:
Operating lease liabilities	27,014
Finance lease liabilities	899
Long-term lease obligations	27,913	$ 0
Total lease obligations	$ 39,478