Supplemental Disclosures of Cash Flow Information - Summary of Supplemental Cash Flow Disclosures (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Supplemental cash flow disclosures:
Cash paid for income taxes, net of cash received	$ 3,905	$ 500
Cash paid for interest	13,928	14,664
Non cash financing activities:
Sinking funds used to retire debt	0	2,939
Conversion of subordinated notes and accrued interest into common stock	37,015	0
Non-cash investing activity:
Contingent earn-out liabilities for acquisitions	767	4,500
Common stock issued for acquisitions	$ 0	$ 3,300