Commitments and contingencies - Additional Information (Detail) (USD $)	12 Months Ended					12 Months Ended		12 Months Ended											12 Months Ended						12 Months Ended				12 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Surety Bond [Member] Waste Control Specialists [Member] Financial Assurance to Texas Government Agencies [Member]	Dec. 31, 2011 Surety Bond [Member] Waste Control Specialists [Member] Financial Assurance to Texas Government Agencies [Member]	Dec. 31, 2012 Additional Collateral Trust [Member] Waste Control Specialists [Member] Financial Assurance to Texas Government Agencies [Member]	Dec. 31, 2011 Additional Collateral Trust [Member] Waste Control Specialists [Member] Financial Assurance to Texas Government Agencies [Member]	Dec. 31, 2012 Additional Collateral Trust [Member] Waste Control Specialists [Member] Financial Assurance to Texas Government Agencies [Member]	Dec. 31, 2012 Customer Concentration Risk [Member] Component Products Segment [Member] Harley Davidson Inc [Member]	Dec. 31, 2011 Customer Concentration Risk [Member] Component Products Segment [Member] Harley Davidson Inc [Member]	Dec. 31, 2010 Customer Concentration Risk [Member] Component Products Segment [Member] Harley Davidson Inc [Member]	Dec. 31, 2010 Customer Concentration Risk [Member] Component Products Segment [Member] San Mateo Postal Data [Member]	Dec. 31, 2012 Customer Concentration Risk [Member] Component Products Segment [Member] Top Ten Customers [Member]	Dec. 31, 2011 Customer Concentration Risk [Member] Component Products Segment [Member] Top Ten Customers [Member]	Dec. 31, 2010 Customer Concentration Risk [Member] Component Products Segment [Member] Top Ten Customers [Member]	Dec. 31, 2012 Chemicals [Member] TiO2 Product [Member] Customer	Dec. 31, 2011 Chemicals [Member] TiO2 Product [Member]	Dec. 31, 2010 Chemicals [Member] TiO2 Product [Member]	Dec. 31, 2012 Chemicals [Member] Customer Concentration Risk [Member] Top Ten Customers [Member]	Dec. 31, 2011 Chemicals [Member] Customer Concentration Risk [Member] Top Ten Customers [Member]	Dec. 31, 2010 Chemicals [Member] Customer Concentration Risk [Member] Top Ten Customers [Member]	Dec. 31, 2012 Chemical Segment [Member] Feedstock Ore [Member]	Dec. 31, 2012 Chemical Segment [Member] Other Supply And Service Contracts [Member]	Dec. 31, 2012 Other Environmental Cleanup Matters [Member]	Dec. 31, 2012 Environmental Remediation Sites Nl Named As Prp Or Defendant [Member] site	Dec. 31, 2012 NL [Member] Cases	Dec. 31, 2011 NL [Member] Insurance claims [Member] Lead Pigment Litigation With Insurance Carriers [Member]	Dec. 31, 2009 NL [Member] Insurance claims [Member] Lead Pigment Litigation With Insurance Carriers [Member]	Dec. 31, 2012 NL [Member] Pending Claims [Member] Product Liability and Occupational Exposure Litigation Claims [Member] Plaintiff Cases	Dec. 31, 2012 NL [Member] Administratively Dismissed Claims [Member] Product Liability and Occupational Exposure Litigation Claims [Member] Plaintiff	May 31, 2010 NL [Member] Litigation Settlement [Member]	Dec. 31, 2012 NL [Member] Litigation Settlement [Member]	Dec. 31, 2011 NL [Member] Litigation Settlement [Member]	Dec. 31, 2010 NL [Member] Litigation Settlement [Member]	Dec. 31, 2012 Certain Environmental Remediation Payments Discounted To Present Value [Member]	Dec. 31, 2012 Behr Process Corporation [Member] Chemicals [Member] Customer Concentration Risk [Member]	Dec. 31, 2012 WCS [Member]
Commitments And Contingent Liabilities [Line Items]
Number of cases settled and dismissed and found not liable																										100
Period by which loss contingency claims settled and dismissed																										20 years
Additions charged to expense, net																										$ 11,300,000									$ 5,600,000
Aggregate payments related to additions charged to expense on undiscounted basis																										6,000,000
Payments related to additions charged to expense on undiscounted basis, 2012																										2,000,000
Payments related to additions charged to expense on undiscounted basis, 2013																										1,000,000
Payments related to additions charged to expense on undiscounted basis, 2014																										1,000,000
Payments related to additions charged to expense on undiscounted basis, 2015																										1,000,000
Payments related to additions charged to expense on undiscounted basis, 2016																										1,000,000
Discount rate																										3.00%
Aggregate payments related to additions charged to expense on discounted basis																										400,000
Accrual for other environmental cleanup matters																								2,200,000	48,000,000
Number of sites associated with remediation ad related costs																									50
Upper end range, estimate costs for remediation and related matters																									144,000,000
Number of sites for which NL not currently able to estimate costs																									5
Insurance recoveries reimbursed																											16,900,000	7,200,000
Cash paid for litigation settlement			19,000,000																												26,000,000
Promissory note issued for litigation settlement																															18,000,000	18,000,000
Principal amount paid on promissory note																																9,000,000	9,000,000
Litigation settlement expense			32,200,000																													32,200,000
Increase in estimate of litigation settlement payment																																		2,100,000
Type of cases pending																													1,125
Number of plaintiffs involved																													1,945	8,125
Sale of TiO2, percentage																90.00%	92.00%	90.00%
Sale made to number of customers, TiO2																4,000
Percentage of sale to top ten customers													38.00%	39.00%	38.00%				34.00%	30.00%	27.00%
Net Sales to Major Customer As a Percentage of Total Net Sales									12.00%	13.00%	12.00%	11.00%																								10.00%
Minimum purchase commitments																						1,800,000,000	122,000,000
Rent expense	16,300,000	13,300,000	11,200,000
Surety bond purchased from third party insurance company				23,400,000	20,000,000
Collateral trust as a percent of value of bonds							2.50%
Cash payments to collateral trust						2,500,000		122,400,000
Surety bond purchased of state of texas in aggregate				12,350,000
Noncurrent restricted cash	$ 20,900,000	$ 7,600,000																																			$ 9,000,000