OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension and postretirement benefits [Abstract]
Amortization of net actuarial loss, Gross Amount	[1]	$ (87)	$ 591	$ 463	$ 1,159
Amortization of net actuarial loss, Income Tax (Provision) Benefit	[1]	21	(143)	(118)	(281)
Amortization of net actuarial loss, Net Amount	[1]	(66)	448	345	878
Actuarial gains (losses), Gross Amount	[1]	8,167	(609)	8,167	(609)
Actuarial gains (losses), Income Tax (Provision) Benefit	[1]	(2,044)	148	(2,044)	148
Actuarial gains (losses), Net Amount	[1]	6,123	(461)	6,123	(461)
Reclassification to retained earnings of stranded tax effects from tax reform, Gross Amount				0	0
Reclassification to retained earnings of stranded tax effects from tax reform, Income Tax (Provision) Benefit				0	(7,925)
Reclassification to retained earnings of stranded tax effects from tax reform, Net Amount				0	(7,925)
Foreign currency translation, Gross Amount		(53)	(429)	76	(9)
Foreign currency translation, Income Tax (Provision) Benefit		0	0	0	0
Foreign currency translation, Net Amount		(53)	(429)	76	(9)
Total other comprehensive income, Gross Amount		8,027	(447)	8,706	541
Total other comprehensive income, Income Tax (Provision) Benefit		(2,023)	5	(2,162)	(8,058)
Total other comprehensive income (loss), net of taxes		$ 6,004	$ (442)	$ 6,544	$ (7,517)

[1] Actuarial gains/(losses) are amortized into other income (expense). (See Note 13 - Retirement Plans)