BASIS OF PRESENTATION RECLASSIFICATIONS FOR ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 138,525	$ 0
Total operating lease liabilities	145,849
Retained earnings	2,266,902	2,191,471
Accumulated other comprehensive loss	(304,779)	$ (288,447)	$ (216,840)
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	151,000
Total operating lease liabilities	151,000
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	26,257
Accumulated other comprehensive loss	$ (26,257)