INCOME TAXES - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax at statutory rate	$ 63,243	$ 71,835	$ 55,864
State income taxes (benefits), net of federal tax effect	2,396	2,622	(1,516)
Investment incentives	(483)	(2,530)	(1,900)
Tax resolutions	820	(1,915)	(3,400)
Excess tax benefits from share-based compensation	(11,625)	(15,370)	(13,400)
Deferred tax charges (benefits), incl. tax rate changes	4,110	0	(2,800)
U.S. Global Intangible Low-Taxed Income ("GILTI") and Base Erosion Anti-Abuse Tax ("BEAT")	(3,909)	(1,485)	5,625
U.S. tax reform - transition tax	0	0	(2,570)
Valuation allowance	1,332	10,623	3,170
Rate differential on earnings of foreign operations	24,901	32,657	29,024
Other items, net	6,280	3,405	3,157
Actual income tax provision	$ 87,065	$ 99,842	$ 71,254
Effective income tax rate	28.90%	29.20%	26.80%