Goodwill - Schedule of Reconciliation of Activity for Goodwill (Detail) - USD ($) $ in Thousands		6 Months Ended
		Jul. 01, 2018	Jul. 02, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance - goodwill		$ 169,316	$ 144,586
Goodwill, System Transformation Transactions acquisitions			15,076
Goodwill, Measurement period adjustments	[1]	1,583	765
Ending balance - goodwill		$ 170,899	$ 160,427

[1] Measurement period adjustments relate to post-closing adjustments made in accordance with the terms and conditions of the applicable asset purchase agreement or asset exchange agreement for each System Transformation Transaction. See Note 3 to the consolidated condensed financial statements for additional information on the System Transformation Transactions.