Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 32,923	$ 27,896	$ 63,639	$ 59,808
Other comprehensive income :
Foreign currency translation adjustments (Note 10)	(35,059)	5,997	(26,242)	16,451
Defined benefit pension adjustments, net of tax (Note 10)	752	567	1,505	1,132
Derivative instrument activity, net of tax (Note 10)	(2)	(3)	(5)	(5)
Total other comprehensive income	(34,309)	6,561	(24,742)	17,578
Comprehensive income (loss)	(1,386)	34,457	38,897	77,386
Comprehensive (income) loss attributable to noncontrolling interests (Note 2)	49	(34)	24	(46)
Comprehensive income (loss) attributable to Stepan Company	$ (1,337)	$ 34,423	$ 38,921	$ 77,340

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 of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (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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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan.

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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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