Commitments and contingencies - Additional Information (Details) $ in Thousands		1 Months Ended		3 Months Ended	12 Months Ended
	Jul. 24, 2019 USD ($) defendant installment	Oct. 31, 2025 USD ($)	Feb. 28, 2025 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) site	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Commitments and contingencies
Litigation settlement amount			$ 151,100
Recognized accretion expense					$ 236	$ 479	$ 695
Accrual for reasonably estimable environmental remediation and related matters					$ 13,040	69,278	91,106	$ 92,358
Litigation settlement amount payable				$ 56,100
Litigation settlement interest				500
Litigation settlement from other party				$ 9,600
Aggregate income						31,400
Insurance recoveries						$ 1,369	$ 464
Component Products | Customer Concentration Risk | Top Ten Customers | Revenue Benchmark
Commitments and contingencies
Concentration risk percentage					52.00%	47.00%	52.00%
Component Products | Customer Concentration Risk | Customer Two | Revenue Benchmark | CompX Security Products Business
Commitments and contingencies
Concentration risk percentage					26.00%	21.00%	24.00%
Component Products | Customer Concentration Risk | Customer Two | Revenue Benchmark | CompX Security Products Business | Pilot project
Commitments and contingencies
Concentration risk percentage							11.00%
Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments and contingencies
Accrual for reasonably estimable environmental remediation and related matters					$ 13,000
Number of sites associated with remediation and related costs | site					27
Number of sites currently not able to reasonably estimate a range of costs | site					5
Maximum | Environmental Remediation Sites NL Named As PRP Or Defendant
Commitments and contingencies
Upper end range, estimate costs for remediation and related matters					$ 26,000
Lead Pigment Litigation
Commitments and contingencies
Description of defendants					on July 24, 2019, an order approving a global settlement agreement entered into among all of the plaintiffs and the three defendants remaining in the case (the Sherwin Williams Company, ConAgra Grocery Products and us) was entered by the court and the case was dismissed with prejudice. The global settlement agreement provided that an aggregate $305 million would be paid collectively by the three co-defendants in full satisfaction of all claims resulting in a dismissal of the case with prejudice and the resolution of (i) all pending and future claims by the plaintiffs in the case, and (ii) all potential claims for contribution or indemnity between us and our co-defendants in respect to the case
Litigation settlement amount	$ 305,000
Number of defendants | defendant	3
NL's portion of global settlement amount, gross value	$ 101,700
Litigation initial payment made 60 days after litigation settlement	25,000
Remaining litigation settlement charge	$ 76,700
Number of annual installments | installment	6
Remaining litigation settlement payment due in first year	$ 12,000
Remaining litigation settlement payment due in second year	12,000
Remaining litigation settlement payment due in third year	12,000
Remaining litigation settlement payment due in forth year	12,000
Remaining litigation settlement payment due in fifth year	12,000
Remaining litigation settlement payment due in sixth year	$ 16,700
Litigation settlement final payment with accrued interest		$ 1,600
Discounted rate for estimated present value of remaining litigation amount	1.90%
Litigation settlement estimated net present value	$ 96,300
Recognized accretion expense					$ 200	$ 500	$ 700
Insurance recoveries					$ 0	$ 1,400	$ 500