INCOME TAXES - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended		3 Months Ended					9 Months Ended		12 Months Ended
	Dec. 31, 2020	Jul. 31, 2020	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Income Tax Contingency [Line Items]
Income tax (benefit) expense			$ (3.0)			$ 6.5		$ 19.9	$ (23.2)
Effective tax rate			4.40%			(8.70%)		209.50%	18.10%
Income tax benefit, CARES Act					$ (5.0)		$ (39.4)
Tax benefit from net operating losses carry back related to CARES Act										$ 44.4
Proceeds from income tax refunds, CARES Act	$ 62.0	$ 48.0
Income taxes receivable, net operating loss, CARES Act	64.2
Interest on income tax expense, CARES Act	$ 2.2
Tax adjustment provision (benefit)				$ (5.5)
Internal Revenue Service | Tax Year 2019
Income Tax Contingency [Line Items]
Income tax refund, CARES Act			$ (1.0)					$ (1.0)