GOODWILL AND OTHER INTANGIBLE ASSETS - Carrying Amount of Goodwill (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill [Roll Forward]
Goodwill - net book value, begging of period	$ 1,428,610,000	$ 1,425,542,000
Merger purchase accounting adjustments	0	2,341,000
Goodwill - net book value, end of period	$ 1,428,610,000	$ 1,427,883,000