GOODWILL AND INTANGIBLE ASSETS - Amortized Intangible Assets - (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Dec. 30, 2017
Components of amortized intangible assets
Gross Carrying Amount	$ 204,077		$ 204,077	$ 216,035
Accumulated Amortization	138,006		138,006	142,289
Amortization expense for intangible assets	3,572	$ 3,903	7,767
Estimated amortization expense
2015	14,187		14,187
2016	12,903		12,903
2017	11,804		11,804
2018	9,748		9,748
2019	7,573		7,573
Customer Relationships
Components of amortized intangible assets
Gross Carrying Amount	188,767		188,767	200,810
Accumulated Amortization	126,904		$ 126,904	$ 131,062
Weighted Average Life			13 years	13 years
Proprietary Software & Database
Components of amortized intangible assets
Gross Carrying Amount	3,589		$ 3,589	$ 3,671
Accumulated Amortization	3,075		$ 3,075	$ 3,107
Weighted Average Life			8 years	8 years
Patents & Proprietary Technology
Components of amortized intangible assets
Gross Carrying Amount	7,225		$ 7,225	$ 6,693
Accumulated Amortization	4,238		$ 4,238	$ 3,999
Weighted Average Life			11 years	11 years
Other
Components of amortized intangible assets
Gross Carrying Amount	4,496		$ 4,496	$ 4,861
Accumulated Amortization	$ 3,789		$ 3,789	$ 4,121
Weighted Average Life			3 years	3 years

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References