Leases - ROU assets and lease liabilities (Detail) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Right-of-use assets
Operating lease assets	$ 58,483	$ 53,758
Finance lease assets	4,035	2,531
Current
Operating lease liabilities	8,232	5,168
Non-current
Operating lease liabilities	59,171	53,940
Operating Right Of Use Assets [Member]
Right-of-use assets
Operating lease assets	58,483	53,758
Property, Plant and Equipment
Right-of-use assets
Finance lease assets	4,035	2,531
Current Operating Lease Liabilities [Member]
Current
Operating lease liabilities	8,232	5,168
Accrued Expenses And Other Current Liabilities [Member]
Current
Finance lease liabilities	1,453	546
Non Current Operating Lease Liabilities [Member]
Non-current
Operating lease liabilities	59,171	53,940
Other Liabilities [Member]
Non-current
Finance lease liabilities	$ 2,631	$ 2,042