ACCUMULATED OTHER COMPREHENSIVE INCOME - Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Accumulated other comprehensive income activity
Balance at the beginning of the period	$ 1,850,389
Other comprehensive income (loss) before reclassifications	(49,442)	$ 14,940
Amounts reclassified from accumulated other comprehensive income	824	9,584
Net current-period other comprehensive income	(48,618)	24,524
Balance at the end of the period	1,957,901
Accumulated Other Comprehensive Income/(Loss)
Accumulated other comprehensive income activity
Balance at the beginning of the period	(281,709)	(341,948)
Balance at the end of the period	(330,327)	(317,424)
Foreign Currency
Accumulated other comprehensive income activity
Balance at the beginning of the period	(178,025)	(257,124)
Other comprehensive income (loss) before reclassifications	(57,317)	19,282
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income	(57,317)	19,282
Balance at the end of the period	(235,342)	(237,842)
Defined Benefit Pension Plans
Accumulated other comprehensive income activity
Balance at the beginning of the period	(102,322)	(83,147)
Other comprehensive income (loss) before reclassifications	529	0
Amounts reclassified from accumulated other comprehensive income	7,131	4,639
Net current-period other comprehensive income	7,660	4,639
Balance at the end of the period	(94,662)	(78,508)
Derivatives
Accumulated other comprehensive income activity
Balance at the beginning of the period	(1,362)	(1,677)
Other comprehensive income (loss) before reclassifications	7,346	(4,342)
Amounts reclassified from accumulated other comprehensive income	(6,307)	4,945
Net current-period other comprehensive income	1,039	603
Balance at the end of the period	$ (323)	$ (1,074)