ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated other comprehensive income activity
Balance at the beginning of the period	$ 1,571,916
Other comprehensive (loss) income before reclassifications	44,538	$ (26,254)	$ (41,008)
Amounts reclassified from accumulated other comprehensive income (loss)	15,701	(5,190)	(9,536)
Net current-period other comprehensive (loss) income	60,239	(31,444)	(50,544)
Reclassification of stranded tax effects			(6,658)
Balance at the end of the period	1,850,389	1,571,916
Foreign Currency
Accumulated other comprehensive income activity
Balance at the beginning of the period	(257,124)	(248,401)	(185,503)
Other comprehensive (loss) income before reclassifications	79,099	(8,723)	(62,898)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Net current-period other comprehensive (loss) income	79,099	(8,723)	(62,898)
Reclassification of stranded tax effects			0
Balance at the end of the period	(178,025)	(257,124)	(248,401)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Accumulated other comprehensive income activity
Balance at the beginning of the period	(83,147)	(60,463)	(64,595)
Other comprehensive (loss) income before reclassifications	(25,389)	(25,557)	5,266
Amounts reclassified from accumulated other comprehensive income (loss)	6,214	2,873	5,524
Net current-period other comprehensive (loss) income	(19,175)	(22,684)	10,790
Reclassification of stranded tax effects			(6,658)
Balance at the end of the period	(102,322)	(83,147)	(60,463)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Accumulated other comprehensive income activity
Balance at the beginning of the period	(1,677)	(1,640)	(3,204)
Other comprehensive (loss) income before reclassifications	(9,172)	8,026	16,624
Amounts reclassified from accumulated other comprehensive income (loss)	9,487	(8,063)	(15,060)
Net current-period other comprehensive (loss) income	315	(37)	1,564
Reclassification of stranded tax effects			0
Balance at the end of the period	(1,362)	(1,677)	(1,640)
Accumulated Other Comprehensive (Loss)Income
Accumulated other comprehensive income activity
Balance at the beginning of the period	(341,948)	(310,504)	(253,302)
Reclassification of stranded tax effects			(6,658)
Balance at the end of the period	$ (281,709)	$ (341,948)	$ (310,504)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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