Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 30,716	$ 31,912
Other comprehensive income :
Foreign currency translation adjustments (Note 10)	8,817	10,454
Defined benefit pension adjustments, net of tax (Note 10)	753	565
Derivative instrument activity, net of tax (Note 10)	(3)	(2)
Total other comprehensive income	9,567	11,017
Comprehensive income	40,283	42,929
Comprehensive income attributable to noncontrolling interests (Note 2)	(25)	(12)
Comprehensive income attributable to Stepan Company	$ 40,258	$ 42,917

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 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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