OTHER COMPREHENSIVE INCOME (accumulated other comprehensive loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated other comprehensive loss [Line Items]
Balance, beginning of year	$ (41,433)	$ (47,947)	$ (56,579)
Other comprehensive income (loss) before reclassifications	8,587	5,114	7,160
Amounts reclassified from accumulated other comprehensive loss	1,354	1,400	1,472
Other comprehensive income	9,941	6,514	8,632
Accumulated other comprehensive loss	(31,492)	(41,433)	(47,947)
Balance, end of year	(31,492)	(41,433)	(47,947)
Postretirement benefit plans [Member]
Accumulated other comprehensive loss [Line Items]
Balance, beginning of year	(21,956)	(28,406)	(36,529)
Other comprehensive income (loss) before reclassifications	6,194	5,616	6,594
Amounts reclassified from accumulated other comprehensive loss	331	834	1,529
Other comprehensive income	6,525	6,450	8,123
Accumulated other comprehensive loss	(15,431)	(21,956)	(28,406)
Balance, end of year	(15,431)	(21,956)	(28,406)
Net unrealized loss on available-for-sale debt securities [Member]
Accumulated other comprehensive loss [Line Items]
Balance, beginning of year	(90)	(275)	(323)
Other comprehensive income (loss) before reclassifications	(254)	338	48
Amounts reclassified from accumulated other comprehensive loss	0	(153)	0
Other comprehensive income	(254)	185	48
Accumulated other comprehensive loss	(344)	(90)	(275)
Balance, end of year	(344)	(90)	(275)
Net unrealized loss on cash flow hedge [Member]
Accumulated other comprehensive loss [Line Items]
Balance, beginning of year	(5,351)	(1,097)	0
Other comprehensive income (loss) before reclassifications	2,067	(4,973)	(1,040)
Amounts reclassified from accumulated other comprehensive loss	1,023	719	(57)
Other comprehensive income	3,090	(4,254)	(1,097)
Accumulated other comprehensive loss	(2,261)	(5,351)	(1,097)
Balance, end of year	(2,261)	(5,351)	(1,097)
Currency translation adjustment [Member]
Accumulated other comprehensive loss [Line Items]
Balance, beginning of year	(14,036)	(18,169)	(19,727)
Other comprehensive income (loss) before reclassifications	580	4,133	1,558
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Other comprehensive income	580	4,133	1,558
Accumulated other comprehensive loss	(13,456)	(14,036)	(18,169)
Balance, end of year	$ (13,456)	$ (14,036)	$ (18,169)