Stepan (SCL) 10-Q 1 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 20, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	SCL
Entity Registrant Name	STEPAN CO
Entity Central Index Key	94,049
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		22,522,507

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net Sales		$ 519,866	$ 495,101		$ 1,019,201	$ 963,370
Cost of Sales	[1]	430,586	405,113		840,351	781,263
Gross Profit	[1]	89,280	89,988		178,850	182,107
Operating Expenses:
Selling	[1]	13,369	13,230		28,259	26,686
Administrative	[1]	18,098	17,769		37,537	35,661
Research, development and technical services	[1]	13,720	14,254		27,334	27,633
Deferred compensation expense		(865)	5,016		749	5,392
Total Operating expenses		44,322	50,269		93,879	95,372
Business restructuring expenses (Note 15)		(273)	(586)	[2]	(631)	(1,372)	[2]
Operating Income	[1]	44,685	39,133	[2]	84,340	85,363	[2]
Other Income (Expense):
Interest, net		(2,672)	(2,863)	[2]	(5,823)	(5,855)	[2]
Other, net (Note 14)	[1]	484	793	[2]	1,644	1,885	[2]
Nonoperating Income (Expense), Total		(2,188)	(2,070)		(4,179)	(3,970)
Income Before Provision for Income Taxes		42,497	37,063	[2]	80,161	81,393	[2]
Provision for Income Taxes (Note 17)		9,574	9,167		16,522	21,585
Net Income		32,923	27,896		63,639	59,808
Net (Income) Loss Attributable to Noncontrolling Interests (Note 2)		2	(14)		9	(13)
Net Income Attributable to Stepan Company		$ 32,925	$ 27,882		$ 63,648	$ 59,795
Net Income Per Common Share Attributable to Stepan Company (Note 9):
Basic		$ 1.43	$ 1.21		$ 2.76	$ 2.61
Diluted		$ 1.41	$ 1.19		$ 2.73	$ 2.56
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 9):
Basic		23,039	22,953		23,059	22,927
Diluted		23,295	23,381		23,341	23,356
Dividends Declared Per Common Share		$ 0.23	$ 0.21		$ 0.45	$ 0.41
[1]	The 2017 amounts for the noted line items have been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of Accounting Standards Update (ASU) No. 2017-7, Compensation –Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.
[2]	The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.

Condensed Consolidated Stateme3

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

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 256,736	$ 298,894
Receivables, net	312,220	293,541
Inventories (Note 6)	188,461	172,748
Other current assets	23,136	23,553
Total current assets	780,553	788,736
Property, Plant and Equipment:
Cost	1,632,103	1,603,286
Less: Accumulated depreciation	(1,032,955)	(1,004,843)
Property, plant and equipment, net	599,148	598,443
Goodwill, net	22,972	25,118
Other intangible assets, net	16,035	18,538
Long-term investments (Note 3)	27,229	28,270
Other non-current assets	12,848	11,756
Total assets	1,458,785	1,470,861
Current Liabilities:
Current maturities of long-term debt (Note 13)	24,312	22,500
Accounts payable	201,313	204,977
Accrued liabilities	80,088	92,776
Total current liabilities	305,713	320,253
Deferred income taxes	14,060	10,962
Long-term debt, less current maturities (Notes 13)	262,504	268,299
Other non-current liabilities	114,474	130,433
Commitments and Contingencies (Note 7)
Equity:
Common stock, $1 par value; authorized 60,000,000 shares; 26,278,816 issued shares in 2018 and 26,070,787 issued shares in 2017	26,279	26,071
Additional paid-in capital	177,779	170,408
Accumulated other comprehensive loss (Note 10)	(124,290)	(99,563)
Retained earnings	775,031	721,741
Less: Common treasury stock, at cost, 3,756,309 shares in 2018 and 3,561,509 shares in 2017	(93,559)	(78,561)
Total Stepan Company stockholders’ equity	761,240	740,096
Noncontrolling interests (Note 2)	794	818
Total equity	762,034	740,914
Total liabilities and equity	$ 1,458,785	$ 1,470,861

Condensed Consolidated Balance5

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	26,278,816	26,070,787
Treasury stock, shares	3,756,309	3,561,509

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows From Operating Activities
Net income	$ 63,639	$ 59,808
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	40,500	37,729
Deferred compensation	749	5,392
Realized and unrealized gains on long-term investments	(504)	(2,576)
Stock-based compensation	3,387	4,551
Deferred income taxes	2,463	2,741
Other non-cash items	830	2,972
Changes in assets and liabilities:
Receivables, net	(23,969)	(33,697)
Inventories	(14,409)	(1,477)
Other current assets	442	(2,050)
Accounts payable and accrued liabilities	(18,579)	(11,777)
Pension liabilities	(122)	(58)
Environmental and legal liabilities	(479)	(469)
Deferred revenues	(162)	(162)
Net Cash Provided By Operating Activities	53,786	60,927
Cash Flows From Investing Activities
Expenditures for property, plant and equipment	(43,741)	(38,331)
Business acquisition (Note 16)	(21,475)	(4,339)
Other, net	1,775	(2,184)
Net Cash Used In Investing Activities	(63,441)	(44,854)
Cash Flows From Financing Activities
Revolving debt and bank overdrafts, net	1,893	(7,221)
Other debt repayments	(5,714)	(5,714)
Dividends paid	(10,160)	(9,225)
Company stock repurchased	(12,000)	(1,500)
Stock option exercises	3,274	2,518
Other, net	(4,432)	(1,586)
Net Cash Used In Financing Activities	(27,139)	(22,728)
Effect of Exchange Rate Changes on Cash	(5,364)	4,730
Net Decrease in Cash and Cash Equivalents	(42,158)	(1,925)
Cash and Cash Equivalents at Beginning of Period	298,894	225,743
Cash and Cash Equivalents at End of Period	256,736	223,818
Supplemental Cash Flow Information
Cash payments of income taxes, net of refunds/payments	19,739	18,288
Cash payments of interest	$ 6,444	$ 7,101

Condensed Consolidated Financia

Condensed Consolidated Financial Statements	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Condensed Consolidated Financial Statements	1. CONDENSED CONSOLIDATED FINANCIAL STATEMENTS The condensed consolidated financial statements included herein have been prepared by Stepan Company (the Company), without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) have been condensed or omitted pursuant to such rules and regulations, although management believes that the disclosures are adequate and make the information presented not misleading. In the opinion of management, all adjustments, consisting only of normal recurring accruals, necessary to present fairly the Company’s financial position as of June 30, 2018, results of operations for the three and six months ended June 30, 2018 and 2017, and cash flows for the six months ended June 30, 2018 and 2017, have been included. These financial statements and related footnotes should be read in conjunction with the financial statements and related footnotes included in the Company’s 2017 Annual Report on Form 10-K.

Reconciliations of Equity

Reconciliations of Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Reconciliations of Equity	2. RECONCILIATIONS OF EQUITY Below are reconciliations of total equity, Company equity and equity attributable to noncontrolling interests for the six months ended June 30, 2018 and 2017: (In thousands) Total Equity Stepan Company Equity Noncontrolling Interests’ Equity (3) Balance at January 1, 2018 $ 740,914 $ 740,096 $ 818 Net income 63,639 63,648 (9 ) Dividends (10,160 ) (10,160 ) Common stock purchases (1) (15,184 ) (15,184 ) Stock option exercises 3,274 3,274 Defined benefit pension adjustments, net of tax 1,505 1,505 Translation adjustments (26,242 ) (26,227 ) (15 ) Derivative instrument activity, net of tax (5 ) (5 ) Other (2) 4,293 4,293 Balance at June 30, 2018 $ 762,034 $ 761,240 $ 794 (In thousands) Total Equity Stepan Company Equity Noncontrolling Interests’ Equity (3) Balance at January 1, 2017 $ 635,916 $ 634,604 $ 1,312 Net income 59,808 59,795 13 Dividends (9,225 ) (9,225 ) — Common stock purchases (1) (3,191 ) (3,191 ) — Stock option exercises 2,518 2,518 — Defined benefit pension adjustments, net of tax 1,132 1,132 — Translation adjustments 16,451 16,418 33 Derivative instrument activity, net of tax (5 ) (5 ) — Other (2) 5,295 5,295 — Balance at June 30, 2017 $ 708,699 $ 707,341 $ 1,358 (1) (2) Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (3)

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. FAIR VALUE MEASUREMENTS The following were the financial instruments held by the Company at June 30, 2018, and December 31, 2017, and the methods and assumptions used to estimate the instruments’ fair values: Cash and cash equivalents Carrying value approximated fair value because of the short maturity of the instruments. Derivative assets and liabilities Derivative assets and liabilities included the foreign currency exchange contracts discussed in Note 4. Fair value and carrying value were the same because the contracts were recorded at fair value. The fair values of the foreign currency contracts were calculated as the difference between the applicable forward foreign exchange rates at the reporting date and the contracted foreign exchange rates multiplied by the contracted notional amounts. See the table that follows the financial instrument descriptions for the reported fair values of derivative assets and liabilities. Long-term investments Long-term investments included the mutual fund assets the Company held to fund a portion of its deferred compensation liabilities and all of its non-qualified supplemental executive defined contribution obligations (see the defined contribution plans section of Note 8). Fair value and carrying value were the same because the mutual fund assets were recorded at fair value. Fair values for the mutual funds were calculated using the published market price per unit at the reporting date multiplied by the number of units held at the reporting date. See the table that follows the financial instrument descriptions for the reported fair value of long-term investments. Debt obligations The fair value of debt with original maturities greater than one year comprised the combined present values of scheduled principal and interest payments for each of the various loans, individually discounted at rates equivalent to those which could be obtained by the Company for new debt issues with durations equal to the average life to maturity of each loan. The fair values of the remaining Company debt obligations approximated their carrying values due to the short-term nature of the debt. The Company’s fair value measurements for debt fall within level 2 of the fair value hierarchy. At June 30, 2018, and December 31, 2017, the fair values and related carrying values of debt, including current maturities, were as follows (the fair value and carrying value amounts are presented without regard to unamortized debt issuance costs of $1,067,000 and $987,000 as of June 30, 2018 and December 31, 2017, respectively): (In thousands) June 30, 2018 December 31, 2017 Fair value $ 284,254 $ 293,272 Carrying value 287,883 291,786 The following tables present financial assets and liabilities measured on a recurring basis at fair value as of June 30, 2018, and December 31, 2017, and the level within the fair value hierarchy in which the fair value measurements fall: (In thousands) June 30, 2018 Level 1 Level 2 Level 3 Mutual fund assets $ 27,229 $ 27,229 $ — $ — Derivative assets: Foreign currency contracts 295 — 295 — Total assets at fair value $ 27,524 $ 27,229 $ 295 $ — Derivative liabilities: Foreign currency contracts $ 441 $ — $ 441 $ — (In thousands) December 31, 2017 Level 1 Level 2 Level 3 Mutual fund assets $ 28,270 $ 28,270 $ — $ — Derivative assets: Foreign currency contracts 335 — 335 — Total assets at fair value $ 28,605 $ 28,270 $ 335 $ — Derivative liabilities : Foreign currency contracts $ 94 $ — $ 94 $ —

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Instruments	4. DERIVATIVE INSTRUMENTS The Company is exposed to certain risks relating to its ongoing business operations. The primary risk managed by the use of derivative instruments is foreign currency exchange risk. The Company holds forward foreign currency exchange contracts that are not designated as any type of accounting hedge as defined by GAAP. The Company uses these contracts to manage its exposure to exchange rate fluctuations on certain Company subsidiary cash, accounts receivable, accounts payable and other obligation balances that are denominated in currencies other than the entities’ functional currencies. The forward foreign exchange contracts are recognized on the balance sheet as either an asset or a liability measured at fair value. Gains and losses arising from recording the foreign exchange contracts at fair value are reported in earnings as offsets to the losses and gains reported in earnings arising from the re-measurement of the asset and liability balances into the applicable functional currencies. At June 30, 2018, and December 31, 2017, the Company had open forward foreign currency exchange contracts, all with durations of one to three months, to buy or sell foreign currencies with U.S. dollar equivalent amounts of $48,492,032 and $41,197,000, respectively. The fair values of the derivative instruments held by the Company on June 30, 2018, and December 31, 2017, are disclosed in Note 3. Derivative instrument gains and losses for the three- and six- month periods ending June 30, 2018 and 2017, were immaterial. For amounts reclassified out of accumulated other comprehensive income (loss) (AOCI) into earnings for the three- and six- month periods ended June 30, 2018 and 2017, see Note 10.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	5. STOCK-BASED COMPENSATION On June 30, 2018, the Company had stock options and stock awards outstanding under its 2006 Incentive Compensation Plan and stock options, stock awards and stock appreciation rights (SARs) outstanding under its 2011 Incentive Compensation Plan. SARs granted prior to 2015 are cash-settled, and SARs granted after 2014 are stock-settled. Stock options and SARs granted prior to 2017 generally cliff vested after two years. Starting in 2017, stock options and SARs have a three-year graded vesting feature, with one-third of the awards vesting each year. The Company has elected the straight-line method of expense attribution for the stock options and SARs with the graded vesting feature. Compensation expense recorded for all stock options, stock awards and SARs was as follows: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 $ 1,155 $ 3,166 $ 3,387 $ 4,551 The year-over-year and quarter-over-quarter decrease in stock-based compensation expense was primarily attributable to cash-settled SARs. SARs compensation expense decreased due to a decrease in the fair values of cash-settled SARs that resulted from a decline in the market value of Company common stock during the first six months of 2018. Unrecognized compensation costs for stock options, stock awards and SARs were as follows: (In thousands) June 30, 2018 December 31, 2017 Stock options $ 2,175 $ 1,179 Stock awards 5,105 3,737 SARs 4,674 2,398 The increases in unrecognized compensation costs for stock options, stock awards and SARs reflected the 2018 grants of: Shares Stock options 76,409 Stock awards (at target) 48,911 SARs 169,245 The unrecognized compensation costs at June 30, 2018, are expected to be recognized over weighted-average periods of 2.2 years, 1.9 years and 2.2 years for stock options, stock awards and SARs, respectively.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Inventories	6. INVENTORIES The composition of inventories at June 30, 2018, and December 31, 2017, was as follows: (In thousands) June 30, 2018 December 31, 2017 Finished goods $ 124,959 $ 117,529 Raw materials 63,502 55,219 Total inventories $ 188,461 $ 172,748 Inventories are priced primarily using the last-in, first-out inventory valuation method. If the first-in, first-out inventory valuation method had been used for all inventories, inventory balances would have been approximately $35,846,000 and $33,518,000 higher than reported at June 30, 2018, and December 31, 2017, respectively.

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Contingencies	7. CONTINGENCIES There are a variety of legal proceedings pending or threatened against the Company. Some of these proceedings may result in fines, penalties, judgments or costs being assessed against the Company at some future time. The Company’s operations are subject to extensive local, state and federal regulations, including the U.S. Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) and the Superfund amendments of 1986 (Superfund) as well as similar regulations in other countries where the Company operates. Over the years, the Company has received requests for information related to or has been named by the government as a potentially responsible party (PRP) at a number of waste disposal sites where cleanup costs have been or may be incurred under CERCLA and similar state statutes. In addition, damages are being claimed against the Company in general liability actions for alleged personal injury or property damage in the case of some disposal and plant sites and in other commercial disputes. The Company believes that it has made adequate provisions for the costs it may incur with respect to these matters. As of June 30, 2018, the Company estimated a range of possible environmental and legal losses of $23.8 million to $45.2 million. At June 30, 2018, and December 31, 2017, the Company’s accrued liability for such losses, which represented the Company’s best estimate within the estimated range of possible environmental and legal losses, was $23.8 million and $24.2 million, respectively. Cash outlays related to legal and environmental matters approximated $0.6 million and $1.0 million for the six-month periods ended June 30, 2018 and 2017, respectively. For certain sites, the Company has responded to information requests made by federal, state or local government agencies but has received no response confirming or denying the Company’s stated positions. As such, estimates of the total costs, or range of possible costs, of remediation, if any, or the Company’s share of such costs, if any, cannot be determined with respect to these sites. Consequently, the Company is unable to predict the effect thereof on the Company’s financial position, cash flows and results of operations. Given the information available, management believes the Company has no liability at these sites. Based upon the Company’s present knowledge with respect to its involvement at these sites, the possibility of other viable entities’ responsibilities for cleanup, and the extended period over which any costs would be incurred, the Company believes that these matters, individually and in the aggregate, will not have a material effect on the Company’s financial position. However, in the event of one or more adverse determinations with respect to such sites in any annual or interim period, the effect on the Company’s cash flows and results of operations for those periods could be material. Following are summaries of the material contingencies at June 30, 2018: Maywood, New Jersey Site The Company’s property in Maywood, New Jersey and property formerly owned by the Company adjacent to its current site and other nearby properties (Maywood site) were listed on the National Priorities List in September 1983 pursuant to the provisions of CERCLA because of certain alleged chemical contamination. Pursuant to an Administrative Order on Consent entered into between the U.S. Environmental Protection Agency (USEPA) and the Company for property formerly owned by the Company, and the issuance of an order by USEPA to the Company for property currently owned by the Company, the Company has completed various Remedial Investigation Feasibility Studies (RI/FS), and in September, 2014, the USEPA issued its Record of Decision (ROD) for chemically-contaminated soil. The USEPA has not yet issued a ROD for chemically-contaminated groundwater for the Maywood site. Based on the most current information available, the Company believes its recorded liability represents its best estimate of the cost of remediation for the Maywood site. The best estimate of the cost of remediation for the Maywood site could change as the Company continues to hold discussions with the USEPA, as the design of the remedial action progresses, if a groundwater ROD is issued or if other PRPs are identified. The ultimate amount for which the Company is liable could differ from the Company’s current recorded liability. In April 2015, the Company entered into an Administrative Settlement Agreement and Administrative Order on Consent with the USEPA which requires payment of certain costs and performance of certain investigative and design work for chemically-contaminated soil. Based on the Company’s review and analysis of this order, no changes to the Company’s recorded liability for claims associated with soil remediation of chemical contamination were required. In addition, under the terms of a settlement agreement reached on November 12, 2004, the U. S. Department of Justice and the Company agreed to fulfill the terms of a Cooperative Agreement reached in 1985 under which the United States will take title to and responsibility for radioactive waste removal at the Maywood site, including past and future remediation costs incurred by the United States. As such, the Company recorded no liability related to this settlement agreement. D’Imperio Property Site During the mid-1970’s, Jerome Lightman and the Lightman Drum Company disposed of hazardous substances at several sites in New Jersey. The Company was named as a PRP in a lawsuit in the U.S. District Court for the District of New Jersey that involved the D’Imperio Property Site located in New Jersey. In 2016, the PRPs were provided with updated remediation cost estimates which were considered in the Company’s determination of its range of estimated possible losses and liability balance. The changes in range of possible losses and liability balance were immaterial. Remediation work is continuing at this site. Based on current information, the Company believes that its recorded liability represents its best estimate of the cost of remediation for the D’Imperio site. Depending on the ultimate cost of the remediation at this site, the amount for which the Company is liable could differ from the current estimates. Wilmington Site The Company is currently contractually obligated to contribute to the response costs associated with the Company’s formerly-owned site in Wilmington, Massachusetts. Remediation at this site is being managed by its current owner, to whom the Company sold the property in 1980. Under the agreement, once total site remediation costs exceed certain levels, the Company is obligated to contribute up to five percent of future response costs associated with this site with no limitation on the ultimate amount of contributions. The Company has paid the current owner $2.6 million for the Company’s portion of environmental response costs through June 30, 2018. The Company has recorded a liability for its portion of the estimated remediation costs for the site. Depending on the ultimate cost of the remediation at this site, the amount for which the Company is liable could differ from the current estimates. The Company and other prior owners also entered into an agreement in April 2004 waiving certain statute of limitations defenses for claims which may be filed by the Town of Wilmington, Massachusetts, in connection with this site. While the Company has denied any liability for any such claims, the Company agreed to this waiver while the parties continue to discuss the resolution of any potential claim which may be filed. Other U.S. Sites Through the regular environmental monitoring of its plant production sites, the Company discovered levels of chemical contamination that were above thresholds allowed by law at two of its U.S plants. The Company voluntarily reported its results to the applicable state environmental agencies. As a result, the Company is required to perform self-remediation of the affected areas. In the fourth quarter of 2016, the Company recognized a charge for the estimated cost of remediating the sites. Based on current information, the Company believes that its recorded liability for the remediation represents its best estimate of expected costs. However, actual costs could differ from current estimates.

Postretirement Benefit Plans

Postretirement Benefit Plans	6 Months Ended
	Jun. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Postretirement Benefit Plans	8. POSTRETIREMENT BENEFIT PLANS Defined Benefit Pension Plans The Company sponsors various funded qualified and unfunded non-qualified defined benefit pension plans, the most significant of which cover employees in the U.S. and U.K. locations. The U.S. and U.K. defined benefit pension plans are frozen and service benefits are no longer being accrued. Components of Net Periodic Benefit Cost UNITED STATES (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Interest cost $ 1,540 $ 1,662 $ 3,079 $ 3,323 Expected return on plan assets (2,321 ) (2,322 ) (4,642 ) (4,643 ) Amortization of net actuarial loss 936 788 1,873 1,576 Net periodic benefit cost $ 155 $ 128 $ 310 $ 256 UNITED KINGDOM (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Interest cost $ 144 $ 147 $ 292 $ 290 Expected return on plan assets (226 ) (198 ) (457 ) (390 ) Amortization of net actuarial loss 56 95 113 187 Net periodic benefit cost (income) $ (26 ) $ 44 $ (52 ) $ 87 In the first quarter of 2018, the Company implemented ASU No. 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost Employer Contributions U.S. Plans As a result of pension funding relief provisions included in the Highway and Transportation Funding Act of 2014, the Company is not required to make contributions to the funded U.S. qualified defined benefit plans. Approximately $312,000 is expected to be paid related to the unfunded non-qualified plans in 2018. Of such amount, $200,000 had been paid related to the non-qualified plans as of June 30, 2018. U.K. Plan The Company’s U.K. subsidiary expects to contribute approximately $415,000 to its defined benefit pension plan in 2018. Of such amount, $251,000 had been contributed to the plan as of June 30, 2018. Defined Contribution Plans The Company sponsors retirement savings defined contribution plans that cover eligible U.S. and U.K. employees. The Company’s U.S. retirement plans include two qualified plans, one of which is a 401(k) plan and one of which is an employee stock ownership plan, and one non-qualified supplemental executive plan. Historically, the Company made profit sharing contributions into the qualified retirement plans for its U.S. employees. Profit sharing contributions were determined each year using a formula that was applied to Company earnings. The contributions, which were made partly in cash paid to the 401(k) plan and partly in Company common stock, are allocated to participant accounts on the basis of participant base earnings. Effective January 1, 2018, the Company amended its U.S. retirement saving plan and profit sharing formula, which resulted in a higher potential contribution percentage to the U.S. retirement savings plan and a lower potential profit sharing contribution percentage relative to prior years. Defined contribution plan expenses for the Company’s retirement savings plans and profit sharing were as follows: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Retirement savings plans $ 1,706 $ 1,224 $ 3,463 $ 2,483 Profit sharing 1,068 2,108 2,010 3,951 Total defined contribution expense $ 2,774 $ 3,332 $ 5,473 $ 6,434 The Company has a rabbi trust to fund the obligations of its non-qualified supplemental executive defined contribution plans (supplemental plans). The trust comprises various mutual fund investments selected by the participants of the supplemental plans. In accordance with the accounting guidance for rabbi trust arrangements, the assets of the trust and the obligations of the supplemental plans are reported on the Company’s consolidated balance sheets. The Company elected the fair value option for the mutual fund investment assets so that offsetting changes in the mutual fund values and defined contribution plan obligations would be recorded in earnings in the same period. Therefore, the mutual funds are reported at fair value with any subsequent changes in fair value recorded in the consolidated statements of income. The liabilities related to the supplemental plans increase (i.e., supplemental plan expense is recognized) when the value of the trust assets appreciates and decrease when the value of the trust assets declines (i.e., supplemental plan income is recognized). At June 30, 2018, the balance of the trust assets was $1,670,000, which equaled the balance of the supplemental plan liabilities (see the long-term investments section in Note 3 for further information regarding the Company’s mutual fund assets).

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	9. EARNINGS PER SHARE Below are the computations of basic and diluted earnings per share for the three and six months ended June 30, 2018 and 2017: (In thousands, except per share amounts) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Computation of Basic Earnings per Share Net income attributable to Stepan Company $ 32,925 $ 27,882 $ 63,648 $ 59,795 Weighted-average number of common shares outstanding 23,039 22,953 23,059 22,927 Basic earnings per share $ 1.43 $ 1.21 $ 2.76 $ 2.61 Computation of Diluted Earnings per Share Net income attributable to Stepan Company $ 32,925 $ 27,882 $ 63,648 $ 59,795 Weighted-average number of shares outstanding 23,039 22,953 23,059 22,927 Add weighted-average net shares from assumed exercise of options (under treasury stock method) (1) 87 172 103 177 Add weighted-average net shares related to unvested stock awards (under treasury stock method) 2 8 2 8 Add weighted-average net shares from assumed exercise of SARs (under treasury stock method) (1) 99 143 111 143 Add weighted-average contingently issuable net shares related to performance stock awards (under treasury stock method) 68 105 66 101 Weighted-average shares applicable to diluted earnings 23,295 23,381 23,341 23,356 Diluted earnings per share $ 1.41 $ 1.19 $ 2.73 $ 2.56 (1)

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	10. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Below is the change in the Company’s AOCI balance by component (net of income taxes) for the three and six months ended June 30, 2018 and 2017: (In thousands) Foreign Currency Translation Adjustments Defined Benefit Pension Plan Adjustments Cash Flow Hedge Adjustments Total Balance at March 31, 2017 $ (86,334 ) $ (30,225 ) $ 98 $ (116,461 ) Other comprehensive income before reclassifications 5,977 — — 5,977 Amounts reclassified from AOCI — 567 (3 ) 564 Net current-period other comprehensive income 5,977 567 (3 ) 6,541 Balance at June 30, 2017 $ (80,357 ) $ (29,658 ) $ 95 $ (109,920 ) Balance at March 31, 2018 $ (61,776 ) $ (28,340 ) $ 88 $ (90,028 ) Other comprehensive income before reclassifications (35,012 ) — — (35,012 ) Amounts reclassified from AOCI — 752 (2 ) 750 Net current-period other comprehensive income (35,012 ) 752 (2 ) (34,262 ) Balance at June 30, 2018 $ (96,788 ) $ (27,588 ) $ 86 $ (124,290 ) Balance at December 31, 2016 $ (96,775 ) $ (30,790 ) $ 100 $ (127,465 ) Other comprehensive income before reclassifications 16,418 — — 16,418 Amounts reclassified from AOCI — 1,132 (5 ) 1,127 Net current-period other comprehensive income 16,418 1,132 (5 ) 17,545 Balance at June 30, 2017 $ (80,357 ) $ (29,658 ) $ 95 $ (109,920 ) Balance at December 31, 2017 $ (70,561 ) $ (29,093 ) $ 91 $ (99,563 ) Other comprehensive income before reclassifications (26,227 ) — — (26,227 ) Amounts reclassified from AOCI — 1,505 (5 ) 1,500 Net current-period other comprehensive income (26,227 ) 1,505 (5 ) (24,727 ) Balance at June 30, 2018 $ (96,788 ) $ (27,588 ) $ 86 $ (124,290 ) Information regarding the reclassifications out of AOCI for the three and six month periods ended June 30, 2018 and 2017, is displayed below: (In thousands) Amount Reclassified from AOCI (a) AOCI Components Three Months Ended June 30, Six Months Ended June 30, Affected Line Item in Consolidated Statements of Income 2018 2017 2018 2017 Amortization of defined benefit pension actuarial losses $ (992 ) $ (883 ) $ (1,986 ) $ (1,763 ) (b) 240 316 481 631 Tax benefit $ (752 ) $ (567 ) $ (1,505 ) $ (1,132 ) Net of tax Gains and losses on cash flow hedges: Foreign exchange contracts 2 3 5 5 Cost of sales 2 3 5 5 Total before tax — — — — Tax benefit $ 2 $ 3 $ 5 $ 5 Net of tax Total reclassifications for the period $ (750 ) $ (564 ) $ (1,500 ) $ (1,127 ) Net of tax (a) Amounts in parentheses denote expense to statement of income. (b) This component of accumulated other comprehensive income is included in the computation of net periodic benefit cost (see Note 8 for additional details).

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment Reporting	11. SEGMENT REPORTING The Company has three reportable segments: Surfactants, Polymers and Specialty Products. Net sales by segment for the three and six months ended June 30, 2018 and 2017, were as follows: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Segment Net Sales Surfactants $ 356,884 $ 329,334 $ 715,824 $ 651,937 Polymers 140,867 141,187 262,800 267,797 Specialty Products 22,115 24,580 40,577 43,636 Total $ 519,866 $ 495,101 $ 1,019,201 $ 963,370 Segment operating income and reconciliations of segment operating income to consolidated income before income taxes for the three and six months ended June 30, 2018 and 2017, are summarized below: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 (2) 2018 2017 (2) Segment Operating Income Surfactants $ 34,218 $ 31,164 $ 74,469 $ 69,535 Polymers 19,458 21,283 36,352 42,708 Specialty Products 4,240 5,451 3,890 6,737 Segment operating income 57,916 57,898 114,711 118,980 Business restructuring (273 ) (586 ) (631 ) (1,372 ) Unallocated corporate expenses (1) (12,958 ) (18,179 ) (29,740 ) (32,245 ) Consolidated operating income 44,685 39,133 84,340 85,363 Interest expense, net (2,672 ) (2,863 ) (5,823 ) (5,855 ) Other, net 484 793 1,644 1,885 Consolidated income before income taxes $ 42,497 $ 37,063 $ 80,161 $ 81,393 (1) Unallocated corporate expenses primarily comprise corporate administrative expenses (e.g., corporate finance, legal, human resources, information systems, deferred compensation and environmental remediation) that are not included in segment operating income and not used to evaluate segment performance. (2) Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	6 Months Ended
	Jun. 30, 2018
Revenue From Contract With Customer [Abstract]
Revenue from Contracts with Customers	12. REVENUE FROM CONTRACTS WITH CUSTOMERS In the majority of instances the Company deems a contract with a customer to exist when a purchase order is received from a customer for a specified quantity of product or products and the Company acknowledges receipt of such purchase order. In some instances the Company has entered into manufacturing supply agreements with customers but these agreements typically do not bind a customer to any purchase volume requirements and thus an obligation is not created until the customer submits a purchase order to the Company. The Company’s contracts typically have a single performance obligation that is satisfied at the time product is shipped. For a small portion of the business, performance obligations are deemed satisfied when product is delivered to a customer location. Revenue is recognized when performance obligations under terms of a contract with a customer have been satisfied, which is predominantly at a point in time. With the 2018 adoption of ASU 2014-09, revenue is currently recognized when a customer obtains control of a product as compared to the “risk and rewards” criteria used in prior years. However, the adoption of ASU 2014-09 did not have a material impact on the Company’s financial position or results of operations during the first six months of 2018. Payment terms on sales of product typically range from 30 to 60 days and ordinarily do not exceed 75 days. As a result, the Company has concluded it does not provide any significant benefits of financing to its customers. The Company has elected to account for shipping and handling as activities to fulfill a promise to transfer the good. As such, shipping and handling fees billed to customers in a sales transaction are recorded in Net Sales and shipping and handling costs incurred are recorded in Cost of Sales. The Company has elected to exclude from Net Sales any value added, sales and other taxes that it collects concurrently with revenue producing activities. These accounting policy elections are consistent with the manner in which the Company has historically recorded shipping and handling fees and taxes. In some instances, a customer may qualify for a rebate based on the volume of purchases made over a specified period of time, typically a quarterly or annual period. The Company estimates the expected volume of total purchases using actual volumes, customer projections and historical order patterns and accrues for these rebates based on the best available information at the time. These estimated rebates are treated as a reduction to Net Sales with the offset being recognized within Current Liabilities. This methodology is consistent with the manner in which the Company has historically estimated and recorded volume based rebates. In other instances, discounts for early payments are offered to certain customers. These discounts are principally accrued for based on a customer’s historical use of discounts. These estimated early payment discounts are accounted for similarly to volume rebates. These forms of variable consideration are considered part of the transaction price. The Company warrants its products from defects. The Company has concluded that these represent assurance-type warranties as opposed to service-type warranties. Product defects are rare in occurrence. As a result, the Company does not maintain any warranty accruals until such time as it is probable a product defect exists. As of June 30, 2018, the Company did not have any contract assets or contract liabilities. A contract liability would typically arise when an advance or deposit is received from a customer before the Company recognizes revenue. In practice, this is extremely rare as it would require a customer to make a payment prior to a performance obligation being satisfied. If such a situation did arise the Company would maintain a deferred revenue liability until the time a performance obligation has been satisfied. The Company did not recognize any revenue in the current period from any pre-existing contract liability balance. The tables below provides a geographic disaggregation of net sales for the three and six months ended June 30, 2018 and 2017. The Company’s business segmentation by geographic region most effectively captures the nature and economic characteristics of the Company’s revenue streams impacted by economic factors. This regional data is the predominant information used by senior management to assess the financial performance of operating segments and make resource allocation decisions. For the Three Months Ended June 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 218,029 $ 86,966 $ 18,674 $ 323,669 Europe 66,065 45,028 3,441 114,534 Latin America 56,579 633 — 57,212 Asia 16,211 8,240 — 24,451 Total $ 356,884 $ 140,867 $ 22,115 $ 519,866 For the Three Months Ended June 30, 2017 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 199,016 $ 86,925 $ 16,203 $ 302,144 Europe 65,289 46,854 8,377 120,520 Latin America 48,559 960 — 49,519 Asia 16,470 6,448 — 22,918 Total $ 329,334 $ 141,187 $ 24,580 $ 495,101 For the Six Months Ended June 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 438,434 $ 160,440 $ 33,488 $ 632,362 Europe 144,436 86,812 7,089 238,337 Latin America 98,267 1,460 — 99,727 Asia 34,687 14,088 — 48,775 Total $ 715,824 $ 262,800 $ 40,577 $ 1,019,201 For the Six Months Ended June 30, 2017 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 397,259 $ 165,289 $ 31,138 $ 593,686 Europe 128,712 89,257 12,498 230,467 Latin America 92,064 2,258 — 94,322 Asia 33,902 10,993 — 44,895 Total $ 651,937 $ 267,797 $ 43,636 $ 963,370

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	13. DEBT At June 30, 2018, and December 31, 2017, debt comprised the following: (In thousands) Maturity Dates June 30, 2018 December 31, 2017 Unsecured private placement notes 3.95% (net of unamortized debt issuance cost of $381 and $346 for 2018 and 2017, respectively) 2021-2027 $ 99,619 $ 99,654 3.86% (net of unamortized debt issuance cost of $375 and $343 for 2018 and 2017, respectively) 2019-2025 99,625 99,657 4.86% (net of unamortized debt issuance cost of $205 and $191 for 2018 and 2017, respectively) 2018-2023 55,509 55,523 5.88% (net of unamortized debt issuance cost of $99 and $95 for 2018 and 2017, respectively) 2018-2022 22,758 28,476 5.69% (net of unamortized debt issuance cost of $7 and $12 for 2018 and 2017, respectively) 2018 5,707 5,703 Debt of foreign subsidiaries Unsecured bank debt, foreign currency 2018 3,598 1,786 Total debt $ 286,816 $ 290,799 Less current maturities 24,312 22,500 Long-term debt $ 262,504 $ 268,299 On January 30, 2018, the Company entered into a five year committed $350 million multi-currency revolving credit facility that matures on January 30, 2023 with a syndicate of banks. This credit facility replaced the Company’s prior $125 million credit agreement. The Company’s outstanding Note Purchase Agreements were amended effective January 30, 2018 to make certain covenants consistent with those included in the credit agreement. The Company maintains standby letters of credit under its workers’ compensation insurance agreements and for other purposes, as needed from time to time, which are issued under the revolving credit agreement. As of June 30, 2018, the Company had outstanding letters of credit totaling $5,302,000 and no outstanding debt under this agreement. There was $344,698,000 available under the revolving credit agreement as of June 30, 2018. The Company’s loan agreements contain provisions which, among others, require maintenance of certain financial ratios and place limitations on additional debt, investments and payment of dividends. Based on the loan agreement provisions that place limitations on dividend payments, unrestricted retained earnings (i.e., retained earnings available for dividend distribution) were $154,639,000 and $190,495,000 at June 30, 2018 and December 31, 2017, respectively.

Other, Net

Other, Net	6 Months Ended
	Jun. 30, 2018
Other Income And Expenses [Abstract]
Other, Net	14. OTHER, NET Other, net in the consolidated statements of income included the following: (In thousands) Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Foreign exchange gains (losses) $ 116 $ (15 ) $ 1,169 $ (499 ) Investment income 90 49 229 151 Realized and unrealized gains on investments 407 931 504 2,576 Net periodic benefit cost (129 ) (172 ) (258 ) (343 ) Other, net $ 484 $ 793 $ 1,644 $ 1,885 Based on requirements of ASU No. 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, .

Business Restructuring

Business Restructuring	6 Months Ended
	Jun. 30, 2018
Restructuring And Related Activities [Abstract]
Business Restructuring	15. BUSINESS RESTRUCTURING In May 2016, the Company announced plans to shut down its Longford Mills, Ontario, Canada (Longford Mills) manufacturing facility, a part of the Surfactant reportable segment, by December 31, 2016. The shutdown plan was developed as an effort to improve the Company’s asset utilization in North America and to reduce the Company’s fixed cost base. Manufacturing operations at the Longford Mills plant ceased by the end of 2016, and production of goods manufactured at the facility was transferred to other Company production sites in the United States. Decommissioning of the assets is expected to continue throughout 2018. As of June 30, 2018, $5,470,000 of aggregate restructuring expense has been recognized, reflecting $1,594,000 of termination benefits for approximately 30 employees and $3,876,000 for other expenses, principally asset decommissioning costs. Below is a reconciliation of the restructuring liabilities as of March 31, 2018 and June 30, 2018: (In thousands) Termination Benefits Other Expense Total Restructuring liability at December 31, 2017 $ 592 $ 99 $ 691 Expense recognized — 358 358 Amounts paid (140 ) (409 ) (549 ) Foreign currency translation (3 ) (4 ) (7 ) Restructuring liability at March 31, 2018 $ 449 $ 44 $ 493 Expense recognized — 273 273 Amounts paid (79 ) (226 ) (305 ) Foreign currency translation (7 ) (2 ) (9 ) Restructuring liability at June 30, 2018 $ 363 $ 89 $ 452 In June 2017, the Company eliminated 11 positions from manufacturing operations at its Singapore plant, which is part of the Company’s Surfactant segment. The reduction in positions was made to better align the number of personnel with business requirements and to reduce costs at that site. As a result of the reduction in workforce, termination expense of $132,000 was recognized in the consolidated statements of income for the three and six months ended June 30, 2017. There is no more termination liability remaining for this site.

Acquisition

Acquisition	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Acquisition	16. ACQUISITION 2018 Acquisition On March 26, 2018, the Company, through a subsidiary in Mexico, acquired BASF Mexicana, S.A.DE C.V.’s (BASF) production facility in Ecatepec, Mexico and a portion of its related surfactants business. The facility, which is near Mexico City, has over 50,000 metric tons of capacity, 124,000 square feet of warehouse space, a large laboratory and office space. The acquired assets and business are included in the Company’s Surfactants segment. The purchase price of the acquisition was $21,475,000 and was paid with cash on hand. The primary assets acquired were land, buildings, machinery and equipment and inventory. The acquisition was accounted for as a business combination, and, accordingly, the assets acquired were measured and recorded at their estimated fair values. The purchase price allocation remains preliminary as of June 30, 2018 pending finalization of the value of inventory acquired. (In thousands) Assets: Property, plant and equipment $ 14,464 Inventory 4,500 Value-added tax receivables 2,511 Total assets acquired $ 21,475 The acquired business is expected to have minimal impact on the Company’s 2018 financial results. Pro forma financial information for the first six months of 2017 and 2018 has not been included because revenues and earnings of the Company would not have been significantly different than reported had the acquisition date been January 1, 2017.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	17. INCOME TAXES On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (Tax Act). The Tax Act made broad and complex changes to the U.S. tax code. For various reasons that are discussed more fully below, we have not completed our accounting for the income tax effects of certain elements of the Tax Act. If we were able to make reasonable estimates of the effects of elements for which our analysis is not yet complete, we recorded provisional adjustments. If we were not yet able to make reasonable estimates of the impact of certain elements, we have not recorded any adjustments related to those elements and have continued accounting for them in accordance with ASC 740 on the basis of the tax laws in effect before the Tax Act. Our accounting for the Tax Act is incomplete. As noted at year-end, we were able to reasonably estimate certain effects and, therefore, recorded the provisional adjustments related to the following: Reduction of U.S. federal corporate tax rate: The Tax Act reduced the corporate tax rate to 21 percent, effective January 1, 2018. We recorded a provisional adjustment for certain of our deferred tax assets and liabilities associated with the tax rate reduction for the year ended December 31, 2017. We have not made any additional measurement-period adjustments in the first six months of 2018 because such adjustments may be affected by other analyses related to the Tax Act, including, but not limited to, our calculation of deemed repatriation of deferred foreign income and the state tax effect of adjustments made to federal temporary differences. However, we are continuing to gather additional information to complete our accounting for this item and expect to complete our accounting within the prescribed measurement period. Deemed Repatriation Transition Tax: The Transition Tax is a tax on previously untaxed accumulated and current earnings and profits of certain of our foreign subsidiaries. We recorded a provisional Transition Tax obligation for the year ended December 31, 2017. We have not made any additional measurement-period adjustments in the quarter because we are continuing to gather additional information to more precisely compute the amount of the Transition Tax. However, we expect to complete our accounting within the prescribed measurement period. Our accounting for the Tax Act is incomplete. As noted at year-end, we were not yet able to reasonably estimate the effects for the items set forth below. Therefore, no provisional adjustments were recorded: Global intangible low taxed income (GILTI): The Tax Act requires the Company to include certain income (GILTI) of its foreign subsidiaries in gross income. The amount of this inclusion is determined under complex rules, and depends, in part, on the character of income earned by the foreign subsidiaries, the tax bases of those subsidiaries’ assets and the amount of certain interest expenses. Under GAAP, we are allowed to make an accounting policy choice of either (1) treating taxes due on future income inclusions related to GILTI as a current-period expense when incurred (the period cost method) or (2) accounting for such amounts in measuring deferred taxes (the deferred method). Our selection of an accounting policy with respect to the new GILTI tax rules will depend, in part, on analyzing our global income to determine whether we expect to have future income inclusions related to GILTI and, if so, what the impact is expected to be. These determinations depend not only on our current structure and estimated future results of global operations but also our intent and ability to modify our structure and/or our business. Therefore, we have not made any adjustments or estimates related to any potential deferred tax liabilities related to GILTI in our financial statements and have not made a policy decision regarding whether to record deferred tax liabilities related to GILTI. Deductibility of Executive Compensation: The Tax Act amended certain aspects of Section 162(m) of the Internal Revenue Code (Section 162(m)), which generally disallows a tax deduction for annual compensation paid to “covered employees” in excess of $1 million, including eliminating an exception to the deduction limit for “qualified performance-based compensation,” effective for tax years beginning after December 31, 2017. The Tax Act provides for a grandfather provision, pursuant to which remuneration that is provided pursuant to a written binding contract in effect on November 2, 2017, and which has not been modified in any material respect on or after that date, will not be subject to the amendments made to Section 162(m) by the Tax Act and will remain eligible for deduction as qualified performance-based compensation. To the extent available, we intend to continue to treat “qualified performance-based compensation” that is grandfathered under the Tax Act as deductible compensation. We have not yet completed our evaluation of our existing compensation arrangements to determine whether any amounts payable to our Section 162(m) covered employees may continue to constitute qualified performance-based compensation under Section 162(m) and qualify under the grandfather provision. Therefore, we have not made any adjustments or estimates related to any potential tax liabilities in our financial statements related to the amendments to Section 162(m). Cost recovery: We have not yet completed all of the computations necessary or completed an inventory of our 2017 expenditures that qualify for immediate expensing. Therefore, we have not made any adjustments or estimates related to any potential tax liabilities in our financial statements related to immediate expensing. Valuation allowances: The Company must assess whether valuation allowances assessments are affected by various aspects of the Tax Act (e.g., GILTI inclusions and new categories of foreign tax credits). Because, as discussed herein, the Company has recorded no amounts related to certain portions of the Tax Act, any corresponding determination of the need for or change in a valuation allowance has not been completed and no changes to valuation allowances as a result of the Tax Act have been recorded.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2018
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	18. RECENT ACCOUNTING PRONOUNCEMENTS In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-9, Revenue from Contracts with Customers (Topic 606) Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date Revenue from Contracts with Customers In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842) In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory In January 2017, the FASB issued ASU No. 2017-4, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU No. 2017-1, Business Combination (Topic 805): Clarifying the Definition of a Business, In March 2017, the FASB issued ASU No. 2017-7, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities In January 2018, the FASB issued ASU No. 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 In February 2018, the FASB issued ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,

Recent Accounting Pronounceme25

Recent Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-9, Revenue from Contracts with Customers (Topic 606) Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date Revenue from Contracts with Customers In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842) In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory In January 2017, the FASB issued ASU No. 2017-4, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU No. 2017-1, Business Combination (Topic 805): Clarifying the Definition of a Business, In March 2017, the FASB issued ASU No. 2017-7, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities In January 2018, the FASB issued ASU No. 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 In February 2018, the FASB issued ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,

Reconciliations of Equity (Tabl

Reconciliations of Equity (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Reconciliations of Total Equity	Below are reconciliations of total equity, Company equity and equity attributable to noncontrolling interests for the six months ended June 30, 2018 and 2017: (In thousands) Total Equity Stepan Company Equity Noncontrolling Interests’ Equity (3) Balance at January 1, 2018 $ 740,914 $ 740,096 $ 818 Net income 63,639 63,648 (9 ) Dividends (10,160 ) (10,160 ) Common stock purchases (1) (15,184 ) (15,184 ) Stock option exercises 3,274 3,274 Defined benefit pension adjustments, net of tax 1,505 1,505 Translation adjustments (26,242 ) (26,227 ) (15 ) Derivative instrument activity, net of tax (5 ) (5 ) Other (2) 4,293 4,293 Balance at June 30, 2018 $ 762,034 $ 761,240 $ 794 (In thousands) Total Equity Stepan Company Equity Noncontrolling Interests’ Equity (3) Balance at January 1, 2017 $ 635,916 $ 634,604 $ 1,312 Net income 59,808 59,795 13 Dividends (9,225 ) (9,225 ) — Common stock purchases (1) (3,191 ) (3,191 ) — Stock option exercises 2,518 2,518 — Defined benefit pension adjustments, net of tax 1,132 1,132 — Translation adjustments 16,451 16,418 33 Derivative instrument activity, net of tax (5 ) (5 ) — Other (2) 5,295 5,295 — Balance at June 30, 2017 $ 708,699 $ 707,341 $ 1,358 (1) (2) Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (3)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Values and Related Carrying Values of Debt	At June 30, 2018, and December 31, 2017, the fair values and related carrying values of debt, including current maturities, were as follows (the fair value and carrying value amounts are presented without regard to unamortized debt issuance costs of $1,067,000 and $987,000 as of June 30, 2018 and December 31, 2017, respectively): (In thousands) June 30, 2018 December 31, 2017 Fair value $ 284,254 $ 293,272 Carrying value 287,883 291,786
Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value	The following tables present financial assets and liabilities measured on a recurring basis at fair value as of June 30, 2018, and December 31, 2017, and the level within the fair value hierarchy in which the fair value measurements fall: (In thousands) June 30, 2018 Level 1 Level 2 Level 3 Mutual fund assets $ 27,229 $ 27,229 $ — $ — Derivative assets: Foreign currency contracts 295 — 295 — Total assets at fair value $ 27,524 $ 27,229 $ 295 $ — Derivative liabilities: Foreign currency contracts $ 441 $ — $ 441 $ — (In thousands) December 31, 2017 Level 1 Level 2 Level 3 Mutual fund assets $ 28,270 $ 28,270 $ — $ — Derivative assets: Foreign currency contracts 335 — 335 — Total assets at fair value $ 28,605 $ 28,270 $ 335 $ — Derivative liabilities : Foreign currency contracts $ 94 $ — $ 94 $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Compensation Expense Recorded for All Stock Options, Stock Awards and SARs	Compensation expense recorded for all stock options, stock awards and SARs was as follows: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 $ 1,155 $ 3,166 $ 3,387 $ 4,551
Unrecognized Compensation Costs for Stock Options, Stock Awards and SARs	Unrecognized compensation costs for stock options, stock awards and SARs were as follows: (In thousands) June 30, 2018 December 31, 2017 Stock options $ 2,175 $ 1,179 Stock awards 5,105 3,737 SARs 4,674 2,398
Share Based Payment Awards Granted in Period	The increases in unrecognized compensation costs for stock options, stock awards and SARs reflected the 2018 grants of: Shares Stock options 76,409 Stock awards (at target) 48,911 SARs 169,245

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2018
Inventory Disclosure [Abstract]
Composition of Inventories	The composition of inventories at June 30, 2018, and December 31, 2017, was as follows: (In thousands) June 30, 2018 December 31, 2017 Finished goods $ 124,959 $ 117,529 Raw materials 63,502 55,219 Total inventories $ 188,461 $ 172,748

Postretirement Benefit Plans (T

Postretirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost UNITED STATES (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Interest cost $ 1,540 $ 1,662 $ 3,079 $ 3,323 Expected return on plan assets (2,321 ) (2,322 ) (4,642 ) (4,643 ) Amortization of net actuarial loss 936 788 1,873 1,576 Net periodic benefit cost $ 155 $ 128 $ 310 $ 256 UNITED KINGDOM (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Interest cost $ 144 $ 147 $ 292 $ 290 Expected return on plan assets (226 ) (198 ) (457 ) (390 ) Amortization of net actuarial loss 56 95 113 187 Net periodic benefit cost (income) $ (26 ) $ 44 $ (52 ) $ 87
Defined Contribution Plan Expenses for Company's Retirement Savings Plans and Profit Sharing	Defined contribution plan expenses for the Company’s retirement savings plans and profit sharing were as follows: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Retirement savings plans $ 1,706 $ 1,224 $ 3,463 $ 2,483 Profit sharing 1,068 2,108 2,010 3,951 Total defined contribution expense $ 2,774 $ 3,332 $ 5,473 $ 6,434

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	Below are the computations of basic and diluted earnings per share for the three and six months ended June 30, 2018 and 2017: (In thousands, except per share amounts) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Computation of Basic Earnings per Share Net income attributable to Stepan Company $ 32,925 $ 27,882 $ 63,648 $ 59,795 Weighted-average number of common shares outstanding 23,039 22,953 23,059 22,927 Basic earnings per share $ 1.43 $ 1.21 $ 2.76 $ 2.61 Computation of Diluted Earnings per Share Net income attributable to Stepan Company $ 32,925 $ 27,882 $ 63,648 $ 59,795 Weighted-average number of shares outstanding 23,039 22,953 23,059 22,927 Add weighted-average net shares from assumed exercise of options (under treasury stock method) (1) 87 172 103 177 Add weighted-average net shares related to unvested stock awards (under treasury stock method) 2 8 2 8 Add weighted-average net shares from assumed exercise of SARs (under treasury stock method) (1) 99 143 111 143 Add weighted-average contingently issuable net shares related to performance stock awards (under treasury stock method) 68 105 66 101 Weighted-average shares applicable to diluted earnings 23,295 23,381 23,341 23,356 Diluted earnings per share $ 1.41 $ 1.19 $ 2.73 $ 2.56 (1)

Accumulated Other Comprehensi32

Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income	Below is the change in the Company’s AOCI balance by component (net of income taxes) for the three and six months ended June 30, 2018 and 2017: (In thousands) Foreign Currency Translation Adjustments Defined Benefit Pension Plan Adjustments Cash Flow Hedge Adjustments Total Balance at March 31, 2017 $ (86,334 ) $ (30,225 ) $ 98 $ (116,461 ) Other comprehensive income before reclassifications 5,977 — — 5,977 Amounts reclassified from AOCI — 567 (3 ) 564 Net current-period other comprehensive income 5,977 567 (3 ) 6,541 Balance at June 30, 2017 $ (80,357 ) $ (29,658 ) $ 95 $ (109,920 ) Balance at March 31, 2018 $ (61,776 ) $ (28,340 ) $ 88 $ (90,028 ) Other comprehensive income before reclassifications (35,012 ) — — (35,012 ) Amounts reclassified from AOCI — 752 (2 ) 750 Net current-period other comprehensive income (35,012 ) 752 (2 ) (34,262 ) Balance at June 30, 2018 $ (96,788 ) $ (27,588 ) $ 86 $ (124,290 ) Balance at December 31, 2016 $ (96,775 ) $ (30,790 ) $ 100 $ (127,465 ) Other comprehensive income before reclassifications 16,418 — — 16,418 Amounts reclassified from AOCI — 1,132 (5 ) 1,127 Net current-period other comprehensive income 16,418 1,132 (5 ) 17,545 Balance at June 30, 2017 $ (80,357 ) $ (29,658 ) $ 95 $ (109,920 ) Balance at December 31, 2017 $ (70,561 ) $ (29,093 ) $ 91 $ (99,563 ) Other comprehensive income before reclassifications (26,227 ) — — (26,227 ) Amounts reclassified from AOCI — 1,505 (5 ) 1,500 Net current-period other comprehensive income (26,227 ) 1,505 (5 ) (24,727 ) Balance at June 30, 2018 $ (96,788 ) $ (27,588 ) $ 86 $ (124,290 )
Summary of Amounts Reclassifications Out of Accumulated Other Comprehensive Income	Information regarding the reclassifications out of AOCI for the three and six month periods ended June 30, 2018 and 2017, is displayed below: (In thousands) Amount Reclassified from AOCI (a) AOCI Components Three Months Ended June 30, Six Months Ended June 30, Affected Line Item in Consolidated Statements of Income 2018 2017 2018 2017 Amortization of defined benefit pension actuarial losses $ (992 ) $ (883 ) $ (1,986 ) $ (1,763 ) (b) 240 316 481 631 Tax benefit $ (752 ) $ (567 ) $ (1,505 ) $ (1,132 ) Net of tax Gains and losses on cash flow hedges: Foreign exchange contracts 2 3 5 5 Cost of sales 2 3 5 5 Total before tax — — — — Tax benefit $ 2 $ 3 $ 5 $ 5 Net of tax Total reclassifications for the period $ (750 ) $ (564 ) $ (1,500 ) $ (1,127 ) Net of tax (a) Amounts in parentheses denote expense to statement of income. (b) This component of accumulated other comprehensive income is included in the computation of net periodic benefit cost (see Note 8 for additional details).

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Operating Segment	The Company has three reportable segments: Surfactants, Polymers and Specialty Products. Net sales by segment for the three and six months ended June 30, 2018 and 2017, were as follows: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 2018 2017 Segment Net Sales Surfactants $ 356,884 $ 329,334 $ 715,824 $ 651,937 Polymers 140,867 141,187 262,800 267,797 Specialty Products 22,115 24,580 40,577 43,636 Total $ 519,866 $ 495,101 $ 1,019,201 $ 963,370
Reconciliation of Segment Information to Consolidated Financial Statements	Segment operating income and reconciliations of segment operating income to consolidated income before income taxes for the three and six months ended June 30, 2018 and 2017, are summarized below: (In thousands) Three Months Ended June 30 Six Months Ended June 30 2018 2017 (2) 2018 2017 (2) Segment Operating Income Surfactants $ 34,218 $ 31,164 $ 74,469 $ 69,535 Polymers 19,458 21,283 36,352 42,708 Specialty Products 4,240 5,451 3,890 6,737 Segment operating income 57,916 57,898 114,711 118,980 Business restructuring (273 ) (586 ) (631 ) (1,372 ) Unallocated corporate expenses (1) (12,958 ) (18,179 ) (29,740 ) (32,245 ) Consolidated operating income 44,685 39,133 84,340 85,363 Interest expense, net (2,672 ) (2,863 ) (5,823 ) (5,855 ) Other, net 484 793 1,644 1,885 Consolidated income before income taxes $ 42,497 $ 37,063 $ 80,161 $ 81,393 (1) Unallocated corporate expenses primarily comprise corporate administrative expenses (e.g., corporate finance, legal, human resources, information systems, deferred compensation and environmental remediation) that are not included in segment operating income and not used to evaluate segment performance. (2) Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.

Revenue from Contracts with C34

Revenue from Contracts with Customers (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue From Contract With Customer [Abstract]
Geographic Disaggregation of Net Sales	The tables below provides a geographic disaggregation of net sales for the three and six months ended June 30, 2018 and 2017. The Company’s business segmentation by geographic region most effectively captures the nature and economic characteristics of the Company’s revenue streams impacted by economic factors. This regional data is the predominant information used by senior management to assess the financial performance of operating segments and make resource allocation decisions. For the Three Months Ended June 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 218,029 $ 86,966 $ 18,674 $ 323,669 Europe 66,065 45,028 3,441 114,534 Latin America 56,579 633 — 57,212 Asia 16,211 8,240 — 24,451 Total $ 356,884 $ 140,867 $ 22,115 $ 519,866 For the Three Months Ended June 30, 2017 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 199,016 $ 86,925 $ 16,203 $ 302,144 Europe 65,289 46,854 8,377 120,520 Latin America 48,559 960 — 49,519 Asia 16,470 6,448 — 22,918 Total $ 329,334 $ 141,187 $ 24,580 $ 495,101 For the Six Months Ended June 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 438,434 $ 160,440 $ 33,488 $ 632,362 Europe 144,436 86,812 7,089 238,337 Latin America 98,267 1,460 — 99,727 Asia 34,687 14,088 — 48,775 Total $ 715,824 $ 262,800 $ 40,577 $ 1,019,201 For the Six Months Ended June 30, 2017 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 397,259 $ 165,289 $ 31,138 $ 593,686 Europe 128,712 89,257 12,498 230,467 Latin America 92,064 2,258 — 94,322 Asia 33,902 10,993 — 44,895 Total $ 651,937 $ 267,797 $ 43,636 $ 963,370

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	At June 30, 2018, and December 31, 2017, debt comprised the following: (In thousands) Maturity Dates June 30, 2018 December 31, 2017 Unsecured private placement notes 3.95% (net of unamortized debt issuance cost of $381 and $346 for 2018 and 2017, respectively) 2021-2027 $ 99,619 $ 99,654 3.86% (net of unamortized debt issuance cost of $375 and $343 for 2018 and 2017, respectively) 2019-2025 99,625 99,657 4.86% (net of unamortized debt issuance cost of $205 and $191 for 2018 and 2017, respectively) 2018-2023 55,509 55,523 5.88% (net of unamortized debt issuance cost of $99 and $95 for 2018 and 2017, respectively) 2018-2022 22,758 28,476 5.69% (net of unamortized debt issuance cost of $7 and $12 for 2018 and 2017, respectively) 2018 5,707 5,703 Debt of foreign subsidiaries Unsecured bank debt, foreign currency 2018 3,598 1,786 Total debt $ 286,816 $ 290,799 Less current maturities 24,312 22,500 Long-term debt $ 262,504 $ 268,299

Other, Net (Tables)

Other, Net (Tables)	6 Months Ended
	Jun. 30, 2018
Other Income And Expenses [Abstract]
Other Net in Consolidated Statements of Income	Other, net in the consolidated statements of income included the following: (In thousands) Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Foreign exchange gains (losses) $ 116 $ (15 ) $ 1,169 $ (499 ) Investment income 90 49 229 151 Realized and unrealized gains on investments 407 931 504 2,576 Net periodic benefit cost (129 ) (172 ) (258 ) (343 ) Other, net $ 484 $ 793 $ 1,644 $ 1,885

Business Restructuring (Tables)

Business Restructuring (Tables)	6 Months Ended
	Jun. 30, 2018
Restructuring And Related Activities [Abstract]
Reconciliation of Restructuring Liabilities	Below is a reconciliation of the restructuring liabilities as of March 31, 2018 and June 30, 2018: (In thousands) Termination Benefits Other Expense Total Restructuring liability at December 31, 2017 $ 592 $ 99 $ 691 Expense recognized — 358 358 Amounts paid (140 ) (409 ) (549 ) Foreign currency translation (3 ) (4 ) (7 ) Restructuring liability at March 31, 2018 $ 449 $ 44 $ 493 Expense recognized — 273 273 Amounts paid (79 ) (226 ) (305 ) Foreign currency translation (7 ) (2 ) (9 ) Restructuring liability at June 30, 2018 $ 363 $ 89 $ 452

Acquisition (Tables)

Acquisition (Tables)	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Summary of Assets Acquired Measured and Recorded at Estimated Fair Values	The acquisition was accounted for as a business combination, and, accordingly, the assets acquired were measured and recorded at their estimated fair values. (In thousands) Assets: Property, plant and equipment $ 14,464 Inventory 4,500 Value-added tax receivables 2,511 Total assets acquired $ 21,475

Reconciliations of Equity - Rec

Reconciliations of Equity - Reconciliations of Total Equity (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reconciliations of total equity
Beginning Balance				$ 740,914	$ 635,916
Net income		$ 32,923	$ 27,896	63,639	59,808
Dividends				(10,160)	(9,225)
Common stock purchases	[1]			(15,184)	(3,191)
Stock option exercises				3,274	2,518
Defined benefit pension adjustments, net of tax		752	567	1,505	1,132
Translation adjustments		(35,059)	5,997	(26,242)	16,451
Derivative instrument activity, net of tax		(2)	(3)	(5)	(5)
Other	[2]			4,293	5,295
Ending Balance		762,034	708,699	762,034	708,699
Stepan Company Equity [Member]
Reconciliations of total equity
Beginning Balance				740,096	634,604
Net income				63,648	59,795
Dividends				(10,160)	(9,225)
Common stock purchases	[1]			(15,184)	(3,191)
Stock option exercises				3,274	2,518
Defined benefit pension adjustments, net of tax				1,505	1,132
Translation adjustments				(26,227)	16,418
Derivative instrument activity, net of tax				(5)	(5)
Other	[2]			4,293	5,295
Ending Balance		761,240	707,341	761,240	707,341
Noncontrolling Interests' Equity [Member]
Reconciliations of total equity
Beginning Balance	[3]			818	1,312
Net income	[3]			(9)	13
Translation adjustments	[3]			(15)	33
Ending Balance	[3]	$ 794	$ 1,358	$ 794	$ 1,358
[1]	Includes the value of Company shares purchased in the open market and from the Company’s retirement plans and the value of Company common shares tendered by employees to settle statutory withholding taxes related to distributions of deferred performance awards and deferred management incentive compensation and exercises of stock appreciation rights.
[2]	Primarily comprised of activity related to stock-based compensation and deferred compensation. Beginning in 2018, also includes beginning retained earnings adjustment as a result of the Company’s first quarter 2018 adoption of ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory.
[3]	Reflects the noncontrolling interest in the Company’s China joint venture.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Unamortized debt issuance cost	$ 1,067,000	$ 987,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values and Related Carrying Values of Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value	$ 287,883	$ 291,786
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	$ 284,254	$ 293,272

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	$ 27,229	$ 28,270
Derivative assets:
Foreign currency contracts	295	335
Total assets at fair value	27,524	28,605
Derivative liabilities:
Foreign currency contracts	441	94
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	27,229	28,270
Derivative assets:
Total assets at fair value	27,229	28,270
Level 2 [Member]
Derivative assets:
Foreign currency contracts	295	335
Total assets at fair value	295	335
Derivative liabilities:
Foreign currency contracts	$ 441	$ 94

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	$ 48,492,032	$ 41,197,000
Minimum [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative foreign currency exchange contracts durations	1 month
Maximum [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative foreign currency exchange contracts durations	3 months

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018
Stock Option and Stock Appreciation Rights (SARs) Granted Prior to 2017 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	2 years
Stock Option and Stock Appreciation Rights (SARS) Granted in 2017 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Percentage of awards vesting in each year	33.33%
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period for amortization of unrecognized compensation cost	2 years 2 months 12 days
Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period for amortization of unrecognized compensation cost	1 year 10 months 24 days
SARs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period for amortization of unrecognized compensation cost	2 years 2 months 12 days

Stock-Based Compensation - Comp

Stock-Based Compensation - Compensation Expense Recorded for All Stock Options, Stock Awards and SARs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Compensation expense	$ 1,155	$ 3,166	$ 3,387	$ 4,551

Stock-Based Compensation - Unre

Stock-Based Compensation - Unrecognized Compensation Costs for Stock Options, Stock Awards and SARs (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs for stock options, stock awards and SARs	$ 2,175	$ 1,179
Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs for stock options, stock awards and SARs	5,105	3,737
SARs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs for stock options, stock awards and SARs	$ 4,674	$ 2,398

Stock-Based Compensation - Shar

Stock-Based Compensation - Share Based Payment Awards Granted in Period (Detail)	6 Months Ended
	Jun. 30, 2018shares
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted in period	76,409
Stock Awards (at target) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards granted in period	48,911
SARs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards granted in period	169,245

Inventories - Composition of In

Inventories - Composition of Inventories (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished goods	$ 124,959	$ 117,529
Raw materials	63,502	55,219
Total inventories	$ 188,461	$ 172,748

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
LIFO reserve	$ 35,846,000	$ 33,518,000

Contingencies - Additional Info

Contingencies - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Site Contingency [Line Items]
Environmental and legal losses	$ 23,800,000		$ 24,200,000
Cash outlays related to legal and environmental matters	$ 600,000	$ 1,000,000
Contribution for future response costs	5.00%
Wilmington Site [Member]
Site Contingency [Line Items]
Payment of environmental response costs	$ 2,600,000
Minimum [Member]
Site Contingency [Line Items]
Environmental and legal losses	23,800,000
Maximum [Member]
Site Contingency [Line Items]
Environmental and legal losses	$ 45,200,000

Postretirement Benefit Plans -

Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (income)	$ 129	$ 172	$ 258	$ 343
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,540	1,662	3,079	3,323
Expected return on plan assets	(2,321)	(2,322)	(4,642)	(4,643)
Amortization of net actuarial loss	936	788	1,873	1,576
Net periodic benefit cost (income)	155	128	310	256
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	144	147	292	290
Expected return on plan assets	(226)	(198)	(457)	(390)
Amortization of net actuarial loss	56	95	113	187
Net periodic benefit cost (income)	$ (26)	$ 44	$ (52)	$ 87

Postretirement Benefit Plans 52

Postretirement Benefit Plans - Defined Benefit Pension Plans - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018USD ($)
Defined Contribution Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Balance of trust assets	$ 1,670,000
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected payment related to non-qualified plan	312,000
Payments related to non-qualified plans	200,000
U.K Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to qualified plan	415,000
Employer contributions	$ 251,000

Postretirement Benefit Plans 53

Postretirement Benefit Plans - Defined Contribution Plan Expenses for the Company's Retirement Savings Plans and Profit Sharing (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution expense	$ 2,774	$ 3,332	$ 5,473	$ 6,434
Retirement Savings Plans [Member]
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution expense	1,706	1,224	3,463	2,483
Profit Sharing [Member]
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution expense	$ 1,068	$ 2,108	$ 2,010	$ 3,951

Earnings Per Share - Computatio

Earnings Per Share - Computations of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Computation of Basic Earnings per Share
Net income attributable to Stepan Company		$ 32,925	$ 27,882	$ 63,648	$ 59,795
Weighted-average number of common shares outstanding		23,039	22,953	23,059	22,927
Basic earnings per share		$ 1.43	$ 1.21	$ 2.76	$ 2.61
Computation of Diluted Earnings per Share
Net income attributable to Stepan Company		$ 32,925	$ 27,882	$ 63,648	$ 59,795
Weighted-average number of common shares outstanding		23,039	22,953	23,059	22,927
Add weighted-average net shares from assumed exercise of options (under treasury stock method)	[1]	87	172	103	177
Add weighted-average net shares related to unvested stock awards (under treasury stock method)		2	8	2	8
Weighted-average shares applicable to diluted earnings		23,295	23,381	23,341	23,356
Diluted earnings per share		$ 1.41	$ 1.19	$ 2.73	$ 2.56
Stock Appreciation Rights (SARs) [Member]
Computation of Diluted Earnings per Share
Add weighted-average net shares from assumed exercise of options (under treasury stock method)	[1]	99	143	111	143
Performance Stock Award [Member]
Computation of Diluted Earnings per Share
Add weighted-average net shares from assumed exercise of options (under treasury stock method)		68	105	66	101
[1]	Options/SARs to acquire 194,949 and 98,878 shares of Company common stock were excluded from the computations of diluted earnings per share for the three- and six- months ended June 30, 2018, respectively. Options/SARs to acquire 37,261 shares of Company common stock were excluded from the computations of diluted earnings per share for the six months ended June 30, 2017. Inclusion of the instruments would have had antidilutive effects on the computations of the earnings per share.

Earnings Per Share - Computat55

Earnings Per Share - Computations of Basic and Diluted Earnings Per Share (Parenthetical) (Detail) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Options and Stock Appreciation Rights (SARs) [Member]
Earnings Per Share Basic [Line Items]
Options to purchase shares of common stock were excluded from the computations of diluted earnings per share	194,949	98,878	37,261

Accumulated Other Comprehensi56

Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			$ 740,096
Other comprehensive income before reclassifications	$ (35,012)	$ 5,977	(26,227)	$ 16,418
Amounts reclassified from AOCI	750	564	1,500	1,127
Net current-period other comprehensive income	(34,262)	6,541	(24,727)	17,545
Ending Balance	761,240		761,240
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(61,776)	(86,334)	(70,561)	(96,775)
Other comprehensive income before reclassifications	(35,012)	5,977	(26,227)	16,418
Net current-period other comprehensive income	(35,012)	5,977	(26,227)	16,418
Ending Balance	(96,788)	(80,357)	(96,788)	(80,357)
Defined Benefit Pension Plan Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(28,340)	(30,225)	(29,093)	(30,790)
Amounts reclassified from AOCI	752	567	1,505	1,132
Net current-period other comprehensive income	752	567	1,505	1,132
Ending Balance	(27,588)	(29,658)	(27,588)	(29,658)
Cash Flow Hedge Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	88	98	91	100
Amounts reclassified from AOCI	(2)	(3)	(5)	(5)
Net current-period other comprehensive income	(2)	(3)	(5)	(5)
Ending Balance	86	95	86	95
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(90,028)	(116,461)	(99,563)	(127,465)
Ending Balance	$ (124,290)	$ (109,920)	$ (124,290)	$ (109,920)

Accumulated Other Comprehensi57

Accumulated Other Comprehensive Income (Loss) - Summary of Amounts Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income Before Provision for Income Taxes		$ 42,497	$ 37,063	[1]	$ 80,161	$ 81,393	[1]
Tax benefit		(9,574)	(9,167)		(16,522)	(21,585)
Cost of Sales	[2]	430,586	405,113		840,351	781,263
Defined Benefit Pension Plan Adjustments [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension actuarial losses	[3],[4]	(992)	(883)		(1,986)	(1,763)
Tax benefit	[3]	240	316		481	631
Income applicable to common stock	[3]	(752)	(567)		(1,505)	(1,132)
Cash Flow Hedge Adjustments [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income Before Provision for Income Taxes	[3]	2	3		5	5
Income applicable to common stock	[3]	2	3		5	5
Cash Flow Hedge Adjustments [Member] | Foreign exchange contracts [Member] | Amounts Reclassified From Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Cost of Sales	[3]	2	3		5	5
Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income applicable to common stock	[3]	$ (750)	$ (564)		$ (1,500)	$ (1,127)
[1]	The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.
[2]	The 2017 amounts for the noted line items have been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of Accounting Standards Update (ASU) No. 2017-7, Compensation –Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.
[3]	Amounts in parentheses denote expense to statement of income.
[4]	This component of accumulated other comprehensive income is included in the computation of net periodic benefit cost (see Note 8 for additional details).

Segment Reporting - Additional

Segment Reporting - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Reporting - Operating S

Segment Reporting - Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net Sales	$ 519,866	$ 495,101	$ 1,019,201	$ 963,370
Surfactants [Member]
Segment Reporting Information [Line Items]
Net Sales	356,884	329,334	715,824	651,937
Polymers [Member]
Segment Reporting Information [Line Items]
Net Sales	140,867	141,187	262,800	267,797
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 22,115	$ 24,580	$ 40,577	$ 43,636

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation of Segment Information to Consolidated Financial Statements (Detail) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	[2]	Jun. 30, 2018	Jun. 30, 2017	[2]
Segment Reporting Information [Line Items]
Operating income	[1]	$ 44,685		$ 39,133		$ 84,340	$ 85,363
Business restructuring expenses (Note 15)		(273)	$ (358)	(586)		(631)	(1,372)
Interest expense, net		(2,672)		(2,863)		(5,823)	(5,855)
Other, net	[1]	484		793		1,644	1,885
Income Before Provision for Income Taxes		42,497		37,063		80,161	81,393
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income		57,916		57,898		114,711	118,980
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating income		34,218		31,164		74,469	69,535
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating income		19,458		21,283		36,352	42,708
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating income		4,240		5,451		3,890	6,737
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[3]	$ (12,958)		$ (18,179)		$ (29,740)	$ (32,245)
[1]	The 2017 amounts for the noted line items have been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of Accounting Standards Update (ASU) No. 2017-7, Compensation –Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.
[2]	The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.
[3]	Unallocated corporate expenses primarily comprise corporate administrative expenses (e.g., corporate finance, legal, human resources, information systems, deferred compensation and environmental remediation) that are not included in segment operating income and not used to evaluate segment performance.

Revenue from Contracts with C61

Revenue from Contracts with Customers - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018USD ($)
Disaggregation Of Revenue [Line Items]
Contract assets	$ 0
Contract liabilities	$ 0
Minimum [Member]
Disaggregation Of Revenue [Line Items]
Payment terms on sales of product	30 days
Maximum [Member]
Disaggregation Of Revenue [Line Items]
Payment terms on sales of product	60 days
Payment terms on sales of product, ordinary circumstances	75 days

Revenue from Contracts with C62

Revenue from Contracts with Customers - Summary of Geographic Disaggregation of Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation Of Revenue [Line Items]
Net sales	$ 519,866	$ 495,101	$ 1,019,201	$ 963,370
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	323,669	302,144	632,362	593,686
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	114,534	120,520	238,337	230,467
Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	57,212	49,519	99,727	94,322
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	24,451	22,918	48,775	44,895
Surfactants [Member]
Disaggregation Of Revenue [Line Items]
Net sales	356,884	329,334	715,824	651,937
Surfactants [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	218,029	199,016	438,434	397,259
Surfactants [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	66,065	65,289	144,436	128,712
Surfactants [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	56,579	48,559	98,267	92,064
Surfactants [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	16,211	16,470	34,687	33,902
Polymers [Member]
Disaggregation Of Revenue [Line Items]
Net sales	140,867	141,187	262,800	267,797
Polymers [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	86,966	86,925	160,440	165,289
Polymers [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	45,028	46,854	86,812	89,257
Polymers [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	633	960	1,460	2,258
Polymers [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	8,240	6,448	14,088	10,993
Specialty Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	22,115	24,580	40,577	43,636
Specialty Products [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	18,674	16,203	33,488	31,138
Specialty Products [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 3,441	$ 8,377	$ 7,089	$ 12,498

Debt - Debt (Detail)

Debt - Debt (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 286,816	$ 290,799
Less current maturities	24,312	22,500
Long-term debt	262,504	268,299
Unsecured private placement 3.95% note [Member]
Debt Instrument [Line Items]
Total debt	$ 99,619	$ 99,654
Debt instrument interest rate percentage	3.95%	3.95%
Unsecured private placement 3.95% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,021	2,021
Unsecured private placement 3.95% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,027	2,027
Unsecured private placement 3.86% note [Member]
Debt Instrument [Line Items]
Total debt	$ 99,625	$ 99,657
Debt instrument interest rate percentage	3.86%	3.86%
Unsecured private placement 3.86% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,019	2,019
Unsecured private placement 3.86% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,025	2,025
Unsecured private placement 4.86% note [Member]
Debt Instrument [Line Items]
Total debt	$ 55,509	$ 55,523
Debt instrument interest rate percentage	4.86%	4.86%
Unsecured private placement 4.86% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,018	2,018
Unsecured private placement 4.86% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,023	2,023
Unsecured private placement 5.88% note [Member]
Debt Instrument [Line Items]
Total debt	$ 22,758	$ 28,476
Debt instrument interest rate percentage	5.88%	5.88%
Unsecured private placement 5.88% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,018	2,018
Unsecured private placement 5.88% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2,022	2,022
Unsecured private placement 5.69% note [Member]
Debt Instrument [Line Items]
Total debt	$ 5,707	$ 5,703
Debt instrument interest rate percentage	5.69%	5.69%
Maturity Dates	2,018	2,018
Debt of foreign subsidiaries Unsecured bank debt, foreign currency [Member]
Debt Instrument [Line Items]
Total debt	$ 3,598	$ 1,786
Maturity Dates	2,018	2,018

Debt - Debt (Parenthetical) (De

Debt - Debt (Parenthetical) (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized debt issuance cost	$ 1,067,000	$ 987,000
Unsecured private placement 3.95% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	381,000	346,000
Unsecured private placement 3.86% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	375,000	343,000
Unsecured private placement 4.86% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	205,000	191,000
Unsecured private placement 5.88% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	99,000	95,000
Unsecured private placement 5.69% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	$ 7,000	$ 12,000

Debt - Additional Information (

Debt - Additional Information (Detail) - Multi currency revolving credit agreement [Member] - USD ($)	Jan. 30, 2018	Jun. 30, 2018	Jan. 29, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Revolving credit agreement term	5 years
Revolving credit agreement	$ 350,000,000		$ 125,000,000
Credit agreement secured date	Jan. 30, 2023
Letters of Credit Outstanding		$ 5,302,000
Debt Outstanding		0
Unused Revolving credit		344,698,000
Unrestricted retained earnings		$ 154,639,000		$ 190,495,000

Other, Net - Other Net in Conso

Other, Net - Other Net in Consolidated Statements of Income (Detail) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Other Nonoperating Income Expense [Abstract]
Foreign exchange gains (losses)		$ 116	$ (15)		$ 1,169	$ (499)
Investment income		90	49		229	151
Realized and unrealized gains on investments		407	931		504	2,576
Net periodic benefit cost		(129)	(172)		(258)	(343)
Other, net	[1]	$ 484	$ 793	[2]	$ 1,644	$ 1,885	[2]
[1]	The 2017 amounts for the noted line items have been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of Accounting Standards Update (ASU) No. 2017-7, Compensation –Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.
[2]	The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.

Business Restructuring - Additi

Business Restructuring - Additional Information (Detail)	1 Months Ended	3 Months Ended				6 Months Ended
	Jun. 30, 2017Employees	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Jun. 30, 2017USD ($)		Jun. 30, 2018USD ($)Employees	Jun. 30, 2017USD ($)		Dec. 31, 2017USD ($)
Restructuring Cost And Reserve [Line Items]
Business restructuring		$ 273,000	$ 358,000	$ 586,000	[1]	$ 631,000	$ 1,372,000	[1]
Restructuring liability		452,000	493,000			452,000			$ 691,000
Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring liability		363,000	449,000			363,000			592,000
Other Expense [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring		273,000	358,000
Restructuring liability		89,000	$ 44,000			89,000			$ 99,000
Longford Mills [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring						$ 5,470,000
Number positions eliminated | Employees						30
Longford Mills [Member] | Surfactants [Member] | Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring						$ 1,594,000
Longford Mills [Member] | Surfactants [Member] | Other Expense [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring						3,876,000
Singapore [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Number positions eliminated | Employees	11
Restructuring liability		$ 0				$ 0
Singapore [Member] | Surfactants [Member] | Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring				$ 132,000			$ 132,000
[1]	The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.

Business Restructuring - Reconc

Business Restructuring - Reconciliation of Restructuring Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	[1]	Jun. 30, 2018	Jun. 30, 2017	[1]
Restructuring Cost And Reserve [Line Items]
Restructuring liability	$ 493	$ 691			$ 691
Expense recognized	273	358	$ 586		631	$ 1,372
Amounts paid	(305)	(549)
Foreign currency translation	(9)	(7)
Restructuring liability	452	493			452
Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring liability	449	592			592
Amounts paid	(79)	(140)
Foreign currency translation	(7)	(3)
Restructuring liability	363	449			363
Other Expense [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring liability	44	99			99
Expense recognized	273	358
Amounts paid	(226)	(409)
Foreign currency translation	(2)	(4)
Restructuring liability	$ 89	$ 44			$ 89
[1]	The 2017 data has been immaterially changed from the amounts originally reported as a result of the Company’s first quarter 2018 adoption of ASU No. 2017-7, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.

Acquisition - Additional Inform

Acquisition - Additional Information (Detail)	Mar. 26, 2018USD ($)ft²T	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)
Business Acquisition [Line Items]
Paid from cash on hand		$ 21,475,000	$ 4,339,000
BASF Mexicana, S.A. DE C.V. [Member] | Surfactants [Member] | Ecatepec, Mexico [Member]
Business Acquisition [Line Items]
Capacity of production facility expected to be acquired | T	50,000
Warehouse space, laboratory and office space currently expected to be acquired | ft²	124,000
Paid from cash on hand	$ 21,475,000

Acquisition - Summary of Assets

Acquisition - Summary of Assets Acquired Measured and Recorded at Estimated Fair Values (Detail) - BASF Mexicana, S.A. DE C.V. [Member] $ in Thousands	Mar. 26, 2018USD ($)
Assets:
Property, plant and equipment	$ 14,464
Inventory	4,500
Value-added tax receivables	2,511
Total assets acquired	$ 21,475

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018USD ($)
Income Tax Disclosure [Abstract]
Corporate tax rate	21.00%
Change in valuation allowance	$ 0