POSTRETIREMENT BENEFIT PLANS - Net Periodic Benefit Cost of Pension Plans and Other Employee Related Benefit Plans (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 0.6	$ 0.8
Interest cost		3.9	4.1
Expected return on plan assets	[1]	(3.5)	(3.9)
Amortization of prior service cost (benefit)		(1.1)	(1.2)
Amortization of net actuarial loss		2.6	2.8
Total net periodic benefit cost		2.5	2.6
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.4	0.6
Interest cost		2.8	3.0
Expected return on plan assets		(3.4)	(3.8)
Amortization of prior service cost (benefit)		0.2	0.2
Amortization of net actuarial loss		1.5	1.7
Total net periodic benefit cost		1.5	1.7
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.2	0.2
Interest cost		1.1	1.1
Expected return on plan assets		(0.1)	(0.1)
Amortization of prior service cost (benefit)		(1.3)	(1.4)
Amortization of net actuarial loss		1.1	1.1
Total net periodic benefit cost		$ 1.0	$ 0.9

[1] (a) Includes plan administrative expenses of $0.9 and $0.8 for the three months ended March 31, 2018 and 2017, respectively. The prior year plan administrative expenses have been reclassified from the service cost component line to conform to the current year presentation.