Fair Values of Financial Instruments - Summary of Acquisition Related Contingent Consideration Liability (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Business Combination, Contingent Consideration, Liability [Roll Forward]
Payments of acquisition related contingent consideration			$ (31,999)	$ (18,784)
Increase in fair value			35,068	62,017
Level 3
Business Combination, Contingent Consideration, Liability [Roll Forward]
Beginning balance - Level 3 liability	$ 441,113	$ 412,450	446,684	382,898
Payments of acquisition related contingent consideration	(11,468)	(5,948)	(31,999)	(18,784)
Reclassification to current payables	(800)	(60)	(1,100)	(940)
Increase in fair value	19,808	18,749	35,068	62,017
Ending balance - Level 3 liability	$ 448,653	$ 425,191	$ 448,653	$ 425,191