Stockholders' Equity (Deficit), Accumulated Other Comprehensive Income (Loss) and Noncontrolling Interest - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Amortization of Defined Benefit Pension and Other Post-retirement Benefit Plan Items, Actuarial Loss [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications out of AOCI	$ 2.5	$ 1.8
Amortization of Defined Benefit Pension and Other Post-retirement Benefit Plan Items, Prior Service Credits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications out of AOCI	(0.5)	(0.7)
Amortization of Defined Benefit Pension and Other Post-retirement Benefit Plan Items, Pension Settlement [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications out of AOCI	0.4	0.1
Amortization of Defined Benefit Pension and Other Post-retirement Benefit Plan Items [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications out of AOCI	2.4	1.2
Tax provision	(0.6)	(0.3)
Net of tax	1.8	0.9
Cash Flow Hedge - Interest Rate Swap [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net of tax	(0.1)
Realized swap interest	0.1	(0.3)
Tax benefit		0.1
Net of tax	$ 0.1	$ (0.2)