ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ 2,536,568	$ 2,453,577
Amortization		11,450	10,756
Other current period change		796	(29,136)
Adoption of new accounting standard				$ (100,567)
Ending balance		2,607,706	2,460,859
Currency Translation Adjustments and Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(199,713)	(143,773)
Amortization		0	0
Other current period change		7,999	(28,233)
Adoption of new accounting standard				0
Ending balance		(191,714)	(172,006)
Net Actuarial Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(700,384)	(560,153)
Amortization		11,173	10,587
Other current period change		(7,203)	(903)
Adoption of new accounting standard				(98,987)
Ending balance		(696,414)	(649,456)
Prior Service (Cost)/ Credit
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(11,537)	(6,910)
Amortization		277	169
Other current period change		0	0
Adoption of new accounting standard				(1,580)
Ending balance		(11,260)	(8,321)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(911,634)	(710,836)
Adoption of new accounting standard	[1]			$ (100,567)
Ending balance		$ (899,388)	$ (829,783)

[1] Reflects the impact of adopting ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income in 2018, which resulted in a reclassification of stranded tax effects caused by the 2017 Tax Cuts and Jobs Act from accumulated other comprehensive loss to retained earnings.