SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Adopted Accounting Changes (Details) £ in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 30, 2017 USD ($)	Apr. 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	$ 1,996,474	$ 1,954,344		$ 1,964,115
Net sales	698,684		$ 637,473
Adjustments to operating income (loss)	63,960		64,656
Other Nonoperating Income (Expense)	(1,141)		1,045
Adjustments to selling, general, and administrative expense	(105,280)		(99,949)
Adjustments to beginning and ending cash balance	479,663	492,805	425,216			$ 412,516
Adjustments to cash provided by (used in) operating activities	(33,048)		(23,415)
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Nonoperating Income (Expense)	154
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
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	13,378	9,771		$ 9,771
Net sales	27,810	51,507
Adjustments to operating income (loss)	$ 5,074	$ 13,121