Fair Values of Financial Instruments - Summary of Reconciliation of Acquisition Related Contingent Consideration (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Payment of acquisition related contingent consideration				$ 18,312	$ 11,650
(Favorable)/unfavorable fair value adjustment				1,584	23,140
Level 3 [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance - Level 3 liability		$ 374,537	$ 319,102	381,291	253,437
Measurement period adjustments	[1]	(1,279)		813
Payment of acquisition related contingent consideration		(7,049)	(5,094)	(18,312)	(11,650)
Reclassification to current payables			150	(1,540)	(2,080)
(Favorable)/unfavorable fair value adjustment		(2,373)	(5,225)	1,584	23,140
Ending balance - Level 3 liability		$ 363,836	$ 308,933	$ 363,836	308,933
Level 3 [Member] | System Transformation Transactions [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Increase due to acquisitions					$ 46,086

[1] Measurement period adjustments relate to post-closing adjustments made in relation to the April 2017 Transactions and the October 2017 Transactions in accordance with the terms and conditions of the applicable asset purchase agreement or asset exchange agreement. See Note 3 to the consolidated condensed financial statements for additional information on the System Transformation Transactions.