Revenue from Contracts with Customers - Change in Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2018	Dec. 27, 2017
Change in Contract with Customer, Liability [Roll Forward]
December 28, 2017	$ 5,791	$ 5,799
Revenue recognized - beginning balance	5,791
Additional contract liability	80
Revenue recognized - additional contract liability	(1)
March 28, 2018	$ (87)