CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income (loss)	$ 29,630us-gaap_ProfitLoss	$ (54,543)us-gaap_ProfitLoss	$ 79,082us-gaap_ProfitLoss
Other comprehensive income (loss), net of tax:
Marketable securities	(107,057)	48,750	(81,032)
Currency translation	(20,357)	1,349	(3,606)
Total other comprehensive income (loss), net	(147,023)	60,237	(92,011)
Comprehensive income (loss)	(117,393)	5,694	(12,929)
Comprehensive income attributable to noncontrolling interest	1,131	790	3,064
Comprehensive income (loss) attributable to NL stockholders	(118,524)us-gaap_ComprehensiveIncomeNetOfTax	4,904us-gaap_ComprehensiveIncomeNetOfTax	(15,993)us-gaap_ComprehensiveIncomeNetOfTax
Defined Benefit Pension Plans
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	(18,616)	9,758	(6,924)
OPEB
Other comprehensive income (loss), net of tax:
Defined benefit pension plans/ Other postretirement benefit plans	$ (993)	$ 380	$ (449)

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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