ACQUISITIONS - Fair Value of Assets Acquired, Summary (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jul. 01, 2018	Jun. 25, 2017	Dec. 31, 2017	Jun. 30, 2018	May 31, 2018	Apr. 30, 2018	Mar. 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Sep. 30, 2017	Jul. 31, 2017	Apr. 30, 2017	Mar. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 255,874		$ 208,044
Contingent consideration liability	13,300
Net cash paid for business	264,436	$ 83,604
Metal Moulding Corporation [Member]
Business Acquisition [Line Items]
Trade receivables								$ 1,474
Inventories								2,324
Property, plant and equipment								3,000
Prepaid expenses & other								0
Intangible assets								10,626
Goodwill								4,618
Less: Accounts payable and accrued liabilities								789
Less: Deferred tax liability								0
Total net assets acquired								21,253
Contingent consideration liability	1,400							1,400
Net cash paid for business	19,900
Aluminum Metals Company [Member]
Business Acquisition [Line Items]
Trade receivables								3,966
Inventories								5,631
Property, plant and equipment								4,000
Prepaid expenses & other								39
Intangible assets								5,350
Goodwill								1,243
Less: Accounts payable and accrued liabilities								2,462
Less: Deferred tax liability								0
Total net assets acquired								$ 17,767
Indiana Marine Products [Member]
Business Acquisition [Line Items]
Trade receivables							$ 1,962
Inventories							4,286
Property, plant and equipment							1,100
Prepaid expenses & other							13
Intangible assets							17,997
Goodwill							3,659
Less: Accounts payable and accrued liabilities							2,899
Less: Deferred tax liability							0
Total net assets acquired							26,118
Contingent consideration liability	7,900						7,900
Net cash paid for business	18,200
Collins & Company [Member]
Business Acquisition [Line Items]
Trade receivables							2,964
Inventories							9,922
Property, plant and equipment							1,125
Prepaid expenses & other							19
Intangible assets							22,000
Goodwill							6,644
Less: Accounts payable and accrued liabilities							2,667
Less: Deferred tax liability							0
Total net assets acquired							$ 40,007
Dehco Inc [Member]
Business Acquisition [Line Items]
Trade receivables						$ 4,680
Inventories						16,802
Property, plant and equipment						14,175
Prepaid expenses & other						2,101
Intangible assets						14,200
Goodwill						4,100
Less: Accounts payable and accrued liabilities						2,824
Less: Deferred tax liability						0
Total net assets acquired						$ 53,234
Dowco Inc. [Member]
Business Acquisition [Line Items]
Trade receivables					$ 4,592
Inventories					4,410
Property, plant and equipment					5,910
Prepaid expenses & other					1,869
Intangible assets					34,379
Goodwill					10,557
Less: Accounts payable and accrued liabilities					3,991
Less: Deferred tax liability					0
Total net assets acquired					$ 57,726
Marine Accessories Corporation [Member]
Business Acquisition [Line Items]
Trade receivables				$ 2,804
Inventories				6,606
Property, plant and equipment				8,000
Prepaid expenses & other				1,613
Intangible assets				32,733
Goodwill				18,710
Less: Accounts payable and accrued liabilities				4,487
Less: Deferred tax liability				8,373
Total net assets acquired				$ 57,606
Medallion Plastics [Member]
Business Acquisition [Line Items]
Trade receivables													$ 2,233
Inventories													2,605
Property, plant and equipment													1,713
Prepaid expenses & other													118
Intangible assets													3,100
Goodwill													1,342
Less: Accounts payable and accrued liabilities													1,200
Less: Deferred tax liability													0
Total net assets acquired													$ 9,911
Leisure Product Enterprises, LLC [Member]
Business Acquisition [Line Items]
Trade receivables												$ 5,848
Inventories												5,162
Property, plant and equipment												9,225
Prepaid expenses & other												337
Intangible assets												33,275
Goodwill												39,945
Less: Accounts payable and accrued liabilities												6,358
Less: Deferred tax liability												14,140
Total net assets acquired												$ 73,294
Wire Design [Member]
Business Acquisition [Line Items]
Trade receivables											$ 615
Inventories											437
Property, plant and equipment											555
Prepaid expenses & other											21
Intangible assets											5,590
Goodwill											4,052
Less: Accounts payable and accrued liabilities											491
Less: Deferred tax liability											0
Total net assets acquired											$ 10,779
Baymont Inc. [Member]
Business Acquisition [Line Items]
Trade receivables										$ 0
Inventories										1,169
Property, plant and equipment										1,750
Prepaid expenses & other										0
Intangible assets										3,166
Goodwill										1,232
Less: Accounts payable and accrued liabilities										62
Less: Deferred tax liability										0
Total net assets acquired										7,255
Contingent consideration liability	4,000									$ 5,100
Net cash paid for business			3,300
Indiana Transport Inc [Member]
Business Acquisition [Line Items]
Trade receivables									$ 6,379
Inventories									0
Property, plant and equipment									3,550
Prepaid expenses & other									1,309
Intangible assets									31,375
Goodwill									19,293
Less: Accounts payable and accrued liabilities									3,116
Less: Deferred tax liability									0
Total net assets acquired									58,790
LMI, Inc. And Related Companies [Member]
Business Acquisition [Line Items]
Trade receivables									11,222
Inventories									9,086
Property, plant and equipment									4,000
Prepaid expenses & other									994
Intangible assets									36,110
Goodwill									27,937
Less: Accounts payable and accrued liabilities									8,470
Less: Deferred tax liability									0
Total net assets acquired									$ 80,879
Nickell Moulding Company, Inc. [Member]
Business Acquisition [Line Items]
Trade receivables			1,762
Inventories			1,550
Property, plant and equipment			933
Prepaid expenses & other			0
Intangible assets			6,179
Goodwill			2,852
Less: Accounts payable and accrued liabilities			681
Less: Deferred tax liability			0
Total net assets acquired			12,595
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Trade receivables			0
Inventories			250
Property, plant and equipment			2,508
Prepaid expenses & other			0
Intangible assets			0
Goodwill			828
Less: Accounts payable and accrued liabilities			124
Less: Deferred tax liability			0
Total net assets acquired			3,462
Acquired Entities [Member]
Business Acquisition [Line Items]
Trade receivables	22,442		28,059
Inventories	49,981		20,259
Property, plant and equipment	37,310		24,234
Prepaid expenses & other	5,654		2,779
Intangible assets	137,285		118,795
Goodwill	49,531		97,481
Less: Accounts payable and accrued liabilities	20,119		20,502
Less: Deferred tax liability	8,373		14,140
Total net assets acquired	$ 273,711		$ 256,965