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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Adopted Accounting Changes (Details) £ in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018 USD ($)	Dec. 30, 2017 USD ($)	Jul. 01, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jul. 01, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 GBP (£)	Dec. 31, 2016 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 2,023,919	$ 1,954,344		$ 2,023,919		$ 1,964,115
Adjustments to operating income (loss)	63,670		$ 78,450	127,630	$ 143,106
Other Nonoperating Income (Expense)	1,844		(192)	703	853
Adjustments to selling, general, and administrative expense	(111,329)		(104,830)	(216,609)	(204,779)
Adjustments to beginning and ending cash balance	722,588	492,805	448,222	722,588	448,222			$ 412,516
Adjustments to cash provided by (used in) operating activities				(53,658)	(55,730)
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative impact of ASC 606 adoption		9,771
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Nonoperating Income (Expense)	160				$ 314
Adjustments to selling, general, and administrative expense	154
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments to beginning and ending cash balance \| £							£ 10,000
Adjustments to cash provided by (used in) operating activities			$ 12,568
Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative impact of ASC 606 adoption		1,038
Difference between Revenue Guidance in Effect before and after Topic 606 \| Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	11,311	9,771		11,311		$ 9,771
Net sales		51,507
Adjustments to operating income (loss)	$ (3,037)	13,121		$ 2,038
Retained earnings \| Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative impact of ASC 606 adoption		9,771
Retained earnings \| Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative impact of ASC 606 adoption		$ 1,038