Leases - Aggregate minimum lease commitments (Details) - USD ($) $ in Thousands	Dec. 26, 2019	Dec. 27, 2018
Operating Leases
2019		$ 11,317
2020		10,169
2021		9,670
2022		9,910
2023		9,038
2024 and thereafter		80,523
Total minimum lease payments		130,627
Capital Leases
2019	$ 3,606	3,073
2020	2,997	2,978
2021	2,950	2,679
2022	2,840	2,718
2023	2,859	2,718
2024 and thereafter	14,093	16,940
Total minimum lease payments	29,345	31,106
Less: amount representing interest	5,972	6,978
Total lease liabilities	$ 23,373	$ 24,128