Segment Information - Reconciliation of Net Income to EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Segment Reporting, Other Significant Reconciling Item, Consolidated
Net income	$ 23,097	$ 22,356	$ 22,867	$ 38,133
Income tax expense	10,403	12,181	11,600	22,530
Depreciation and amortization	32,771	33,930	66,217	64,828
Interest expense, net	19,076	18,492	35,680	36,148
Impairment and restructuring charges	2,343	6,214	9,038	10,317
(Gain) loss on sale of property and equipment	(337)	568	(2,410)	1,080
Stock-based compensation	5,162	3,882	8,895	6,477
Non-cash foreign exchange transaction/translation (income) loss	8,784	7,484	7,595	3,797
Other items	24,250	22,407	40,575	32,817
Other non-cash items	0	(69)	0	(734)
Costs relating to debt restructuring and debt refinancing	170	0	170	0
Adjusted EBITDA	125,719	127,583	200,227	216,861
Legal fees	22,994	4,640	34,700	6,288
Consolidation and reorganization cost	967	8,324	4,077	13,151
Acquisition-related costs		9,063		11,997
Employee retention cost		7,077		7,077
Miscellaneous cost		274		856
Executive compensation expense		100		525
One-time lease termination charges			1,235
Cost of sales
Segment Reporting, Other Significant Reconciling Item, Consolidated
Impairment and restructuring charges	$ 77	$ 480	$ 227	$ 864