PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS (Additional) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Contribution, Percentage, Maximum			7.00%
Defined Contribution Plan, Cost	$ 4.5	$ 4.2	$ 14.8	$ 13.8
Defined Contribution Plan, Employer Discretionary Contribution Amount			$ 16.5
Forecast [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount					$ 18.3