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BASIS OF PRESENTATION - New Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general and administrative	$ (93,637)	$ (77,976)	$ (178,362)	$ (153,014)
Reclass to Other income, net	(2,792)	(2,169)	(6,794)	(4,360)
Reclass from accumulated other comprehensive income	52,983		52,983		$ 43,774
Retained earnings	$ 366,699		$ 366,699		347,304
ASU 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclass from accumulated other comprehensive income					6,300
Retained earnings					$ 6,300
ASU 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general and administrative		2,400		4,800
Reclass to Other income, net		$ 2,400		$ 4,800