Goodwill and Intangible Assets - Acquired and Amortization (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Acquired identifiable intangible assets
Acquired identifiable intangible assets, net of accumulated amortization	$ 8,881	$ 9,208
Accumulated amortization	3,962	3,636
Non-competition agreements
Acquired identifiable intangible assets
Acquired identifiable intangible assets, net of accumulated amortization	233	260
Accumulated amortization	490	464
Customer relationships
Acquired identifiable intangible assets
Acquired identifiable intangible assets, net of accumulated amortization	8,648	8,948
Accumulated amortization	$ 3,472	$ 3,172