CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Net income	$ 10,357us-gaap_ProfitLoss	$ 4,034us-gaap_ProfitLoss
Other comprehensive income (loss), net of tax:
Marketable securities	(1,786)	(83,931)
Currency translation	(12,959)	(514)
Total other comprehensive loss, net	(14,147)	(84,065)
Comprehensive loss	(3,790)	(80,031)
Comprehensive income attributable to noncontrolling interest	315	279
Comprehensive loss attributable to NL stockholders	(4,105)us-gaap_ComprehensiveIncomeNetOfTax	(80,310)us-gaap_ComprehensiveIncomeNetOfTax
Defined Benefit Pension Plans
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	734	537
OPEB
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	$ (136)	$ (157)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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