PREFERRED STOCK - Additional Information (Detail) $ / shares in Units, $ in Millions			1 Months Ended											12 Months Ended			13 Months Ended
	Sep. 14, 2018 shares	Sep. 15, 2015 USD ($) $ / shares shares	Dec. 31, 2018 shares	Nov. 30, 2018 shares	Oct. 31, 2018 shares	Sep. 30, 2018 shares	Aug. 31, 2018 shares	Jul. 31, 2018 shares	Jun. 30, 2018 shares	May 31, 2018 shares	Apr. 30, 2018 shares	Feb. 28, 2018 shares	Jan. 31, 2018 shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) shares	Mar. 31, 2019 shares
Equity [Abstract]
Preferred stock, authorized (in shares)														1,000,000	1,000,000.0
Preferred stock, issued (in shares)	638,190													0	0
Preferred stock, outstanding (in shares)														0	0
Depositary shares (in shares)		7,700,000
Number of preferred shares each depository share represents (in shares)		0.10
Preferred stock, dividend rate		5.25%
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.01												$ 0.01	$ 0.01
Issuance of preferred stock (in dollars per share) | $ / shares		$ 100.0
Gross proceeds from issuance of preferred stock | $		$ 770.0
Conversion of preferred stock to common stock, (in shares)	4,700,000
Conversion of preferred stock to common stock conversion ratio	7.3394
Preferred stock, liquidation preference (in dollars per share) | $ / shares		$ 1,000
Liquidation preference (in dollars per share) | $ / shares		$ 100.0
Dividends paid on mandatory convertible preferred shareholders | $														$ 0.0	$ 0.0	$ 25.5
Increase to retained earnings on repurchase of depository shares | $														0.0	0.0	$ 16.9
Depositary shares repurchased during period (in shares)			0	0	0	0	50,000	0	0	150,000	0	151,900	0			351,900	0
Depository shares equivalent to preferred stock units (in shares)			35,190													35,190
Accrued Environmental Loss Contingencies, Noncurrent | $														$ 0.0	$ 27.2