EMPLOYEE BENEFIT PLANS - Employee benefit plan amounts recognized in the Consolidated Balance Sheets and Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Retirement Benefits [Abstract]
Service cost	$ 2,350	$ 1,850
Interest cost	525	600
Expected return on plan assets	(2,550)	(2,475)
Amortization of prior service cost	(100)	(100)
Defined Benefit Plan, Amortization of Gain (Loss)	625	525
Net periodic benefit cost (income)	$ 850	$ 400