Commitments and Contingencies - Lead Pigment Litigation-NL and Environmental Matters and Litigation - Additional Information (Detail) $ in Millions	1 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($) site	May 31, 2018 USD ($) Installment	Jun. 30, 2018 USD ($) Installment	Sep. 30, 2018 USD ($) Cases Installment site	Aug. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Commitments And Contingent Liabilities [Line Items]
Litigation settlement net present value	$ 17.0			$ 17.0
Current insurance recovery receivable	15.0			15.0
Accrual for reasonably estimable environmental remediation and related matters	116.7			116.7		$ 117.5
Other Environmental Cleanup Matters
Commitments And Contingent Liabilities [Line Items]
Accrual for reasonably estimable environmental remediation and related matters	5.7			5.7
NL
Commitments And Contingent Liabilities [Line Items]
Recalculated abatement fund amount					$ 409.0
Settlement of recalculated abatement fund amount	409.0
Recalculated abatement fund amount undetermined					409.0
Current insurance recovery receivable	15.0			15.0
NL | Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments And Contingent Liabilities [Line Items]
Accrual for reasonably estimable environmental remediation and related matters	$ 111.0			$ 111.0
Number of sites associated with remediation and related costs | site	37			37
Number of sites for which NL not currently able to reasonably estimate range of costs | site	5			5
NL | Maximum | Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments And Contingent Liabilities [Line Items]
Upper end range, estimate costs for remediation and related matters	$ 130.0			$ 130.0
Lead Pigment Litigation | NL
Commitments And Contingent Liabilities [Line Items]
Number of cases settled and dismissed and found not liable | Cases				100
Period by which loss contingency claims settled and dismissed				20 years
Settlement agreement amount		$ 80.0	$ 45.0
Settlement agreement amount to be paid		65.0	62.0
Litigation settlement charge upon trial court's approval		$ 45.0	$ 45.0
Number of annual installments | Installment		5	5	5
Litigation settlement installments payment beginning term from approval		4 years	4 years
Remaining litigation settlement charge	$ 20.0	$ 20.0	$ 20.0	$ 20.0
Remaining litigation settlement charge due in first installment		6.0
Remaining litigation settlement charge due in second installment		5.0
Remaining litigation settlement charge due in third installment		3.0
Remaining litigation settlement charge due in fourth installment		3.0
Remaining litigation settlement charge due in fifth installment		3.0
Discounted rate for estimated present value of remaining litigation amount	3.00%			3.00%
Litigation settlement net present value	$ 17.0		17.0	$ 17.0
Current insurance recovery receivable			$ 15.0
Lead Pigment Litigation | NL | NL Former Insurance Carriers
Commitments And Contingent Liabilities [Line Items]
Settlement agreement amount to be paid		$ 15.0
California Lead Paint Litigation | NL
Commitments And Contingent Liabilities [Line Items]
Amount awarded to the plaintiff				$ 1,150.0
Lead Pigment Litigation Plaintiffs
Commitments And Contingent Liabilities [Line Items]
Proposed abatement fund amount					$ 730.0