Goodwill and Intangible Assets - Schedule of Goodwill (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Balance at beginning of period	$ 65,999	$ 28,146
Goodwill acquired	1,112	37,853
Measurement period adjustments	(193)
Balance at end of period	$ 66,918	$ 65,999