Stepan (SCL) 10-Q 30 Oct 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 22, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	SCL
Entity Registrant Name	STEPAN CO
Entity Current Reporting Status	Yes
Entity Central Index Key	0000094049
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		22,505,067
Entity Tax Identification Number	36-1823834
Entity File Number	1-4462
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	22 West Frontage Road
Entity Address, City or Town	Northfield
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60093
City Area Code	847
Local Phone Number	446-7500
Security Exchange Name	NYSE
Title of 12(b) Security	Common Stock, $1 par value
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net Sales		$ 451,582	$ 507,997		$ 1,413,755	$ 1,527,198
Cost of Sales	[1]	374,180	424,421		1,158,785	1,262,443
Gross Profit	[1]	77,402	83,576		254,970	264,755
Operating Expenses:
Selling		14,186	14,613		42,295	42,872
Administrative		19,708	21,904		60,558	59,441
Research, development and technical services		13,473	13,977		40,228	41,311
Deferred compensation expense		1,610	4,222		11,478	4,971
Total Operating expenses		48,977	54,716		154,559	148,595
Business restructuring expenses (Note 17)		(459)	(1,715)		(1,642)	(2,346)
Operating Income	[1],[2]	27,966	27,145		98,769	113,814
Other Income (Expense):
Interest, net		(1,402)	(2,797)		(5,021)	(8,620)
Other, net (Note 16)		885	346		4,265	1,990
Nonoperating Income (Expense), Total		(517)	(2,451)		(756)	(6,630)
Income Before Provision for Income Taxes	[1],[2]	27,449	24,694		98,013	107,184
Provision for Income Taxes	[1]	1,569	2,940		16,945	20,033
Net Income	[1],[2]	25,880	21,754	[3]	81,068	87,151	[3]
Net Loss Attributable to Noncontrolling Interests (Note 3)		9			23	9
Net Income Attributable to Stepan Company	[1],[2]	$ 25,889	$ 21,754		$ 81,091	$ 87,160
Net Income Per Common Share Attributable to Stepan Company (Note 11):
Basic	[1],[2]	$ 1.12	$ 0.95		$ 3.52	$ 3.78
Diluted	[1],[2]	$ 1.11	$ 0.93		$ 3.48	$ 3.74
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 11):
Basic		23,025	22,986		23,070	23,036
Diluted		23,300	23,288		23,320	23,324
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[3]	The retained earnings and net income amounts for the noted line items have been changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO .

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	[1],[2]	$ 25,880	$ 21,754	[3]	$ 81,068	$ 87,151	[3]
Other comprehensive income:
Foreign currency translation adjustments (Note 12)	[4]	(19,287)	(2,534)		(11,290)	(28,776)
Defined benefit pension adjustments, net of tax (Note 12)		473	788		1,558	2,293
Derivative instrument activity, net of tax (Note 12)		(2)	(2)		(6)	(7)
Total other comprehensive income		(18,816)	(1,748)		(9,738)	(26,490)
Comprehensive income	[1]	7,064	20,006		71,330	60,661
Comprehensive loss attributable to noncontrolling interests (Note 3)		41	31		62	55
Comprehensive income attributable to Stepan Company	[1]	$ 7,105	$ 20,037		$ 71,392	$ 60,716
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[3]	The retained earnings and net income amounts for the noted line items have been changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO .
[4]	Includes foreign currency translation adjustments related to noncontrolling interest.

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents		$ 285,995	$ 300,194
Receivables, net		283,016	280,025
Inventories (Note 2)(Note 7)	[1]	203,303	231,528
Other current assets		25,714	22,146
Total current assets	[1]	798,028	833,893
Property, Plant and Equipment:
Cost		1,713,245	1,666,790
Less: Accumulated depreciation		(1,101,966)	(1,057,898)
Property, plant and equipment, net		611,279	608,892
Goodwill, net		22,144	22,954
Other intangible assets, net		11,518	14,244
Long-term investments (Note 4)		26,389	25,082
Operating lease assets		38,027
Other non-current assets	[1]	10,985	9,549
Total assets	[1]	1,518,370	1,514,614
Current Liabilities:
Current maturities of long-term debt (Note 15)		24,137	37,058
Accounts payable		175,808	205,954
Accrued liabilities		93,018	95,570
Total current liabilities		292,963	338,582
Deferred income taxes	[1]	25,218	24,961
Long-term debt, less current maturities (Note 15)		207,783	239,022
Non-current operating lease liabilities		29,064
Other non-current liabilities		108,435	103,864
Commitments and Contingencies (Note 9)
Equity:
Common stock, $1 par value; authorized 60,000,000 shares; Issued 26,481,229 shares in 2019 and 26,286,587 shares in 2018		26,481	26,309
Additional paid-in capital		191,404	182,881
Accumulated other comprehensive loss (Note 12)	[2]	(156,507)	(141,483)
Retained earnings	[1],[2]	906,612	837,107
Less: Common treasury stock, at cost, 3,976,162 shares in 2019 and 3,773,946 shares in 2018		(113,781)	(97,389)
Total Stepan Company stockholders' equity	[1]	854,209	807,425
Noncontrolling interests (Note 3)		698	760
Total equity	[1]	854,907	808,185	[3]
Total liabilities and equity	[1]	$ 1,518,370	$ 1,514,614
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The 2019 amounts for the noted line items include an adjustment related to the Company’s first quarter 2019 adoption of ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income
[3]	The retained earnings and net income amounts for the noted line items have been changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO .

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
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	26,481,229	26,286,587
Treasury stock, shares	3,976,162	3,773,946

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Cash Flows From Operating Activities
Net income	[1],[2]	$ 81,068	$ 87,151	[3]
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		58,545	60,778
Deferred compensation		11,478	4,971
Realized and unrealized gains on long-term investments		(2,806)	(1,241)
Stock-based compensation		7,045	6,722
Deferred income taxes	[1]	(2,291)	6,846
Other non-cash items		2,192	1,370
Changes in assets and liabilities:
Receivables, net		(8,959)	(34,807)
Inventories	[1]	25,879	(23,366)
Other current assets		(3,750)	727
Accounts payable and accrued liabilities		(35,330)	(6,906)
Pension liabilities		(979)	(5,059)
Environmental and legal liabilities		800	(763)
Deferred revenues		(243)	(243)
Net Cash Provided By Operating Activities		132,649	96,180
Cash Flows From Investing Activities
Expenditures for property, plant and equipment		(70,829)	(62,895)
Business acquisition (Note 18)			(21,475)
Other, net		2,332	1,684
Net Cash Used In Investing Activities		(68,497)	(82,686)
Cash Flows From Financing Activities
Revolving debt and bank overdrafts, net		(6,929)	1,379
Other debt repayments		(37,143)	(5,714)
Dividends paid		(16,911)	(15,225)
Company stock repurchased		(13,184)	(13,500)
Stock option exercises		2,830	3,488
Other, net		(3,101)	(4,504)
Net Cash Used In Financing Activities		(74,438)	(34,076)
Effect of Exchange Rate Changes on Cash		(3,913)	(4,324)
Net Decrease in Cash and Cash Equivalents		(14,199)	(24,906)
Cash and Cash Equivalents at Beginning of Period		300,194	298,894
Cash and Cash Equivalents at End of Period		285,995	273,988
Supplemental Cash Flow Information
Cash payments of income taxes, net of refunds/payments		21,698	25,190
Cash payments of interest		$ 9,311	$ 8,553
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[3]	The retained earnings and net income amounts for the noted line items have been changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO .

Condensed Consolidated Financia

Condensed Consolidated Financial Statements	9 Months Ended
	Sep. 30, 2019
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 September 30, 2019, and its results of operations for the three and nine months ended September 30, 2019 and 2018, and cash flows for the nine months ended September 30, 2019 and 2018, 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 2018 Annual Report on Form 10-K.

Change In Method of Accounting

Change In Method of Accounting for Inventory Valuation	9 Months Ended
	Sep. 30, 2019
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Change in Method of Accounting for Inventory Valuation	2. CHANGE IN METHOD OF ACCOUNTING FOR INVENTORY VALUTION On January 1, 2019, the Company elected to change its method of accounting for U.S. inventories from the LIFO basis to the FIFO basis. Total U.S. inventories accounted for using the LIFO cost flow assumption, prior to the accounting method change, comprised 68 percent of the Company’s total inventories as of December 31, 2018. Non-U.S. inventories have historically been maintained on the FIFO basis. The Company believes that this change to the FIFO method of inventory valuation is preferable as it provides a better matching of costs with the physical flow of goods, more accurately reflects the current market value of inventory presented on the Company’s consolidated balance sheets, standardizes the Company’s inventory valuation methodology and improves comparability with the Company’s industry peers. In accordance with ASC 250, Accounting Changes and Error Corrections The following tables present the prior year financial statement line items that have been affected by the retrospective change in accounting principle: Income Statement (In thousands, except per share amounts) Three Months Ended September 30, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Cost of Sales $ 423,872 $ 549 $ 424,421 Gross Profit 84,125 (549 ) 83,576 Operating Income 27,694 (549 ) 27,145 Income Before Provision for Income Taxes 25,243 (549 ) 24,694 Provision for Income Taxes 3,075 (135 ) 2,940 Net Income 22,168 (414 ) 21,754 Net Income Attributable to Stepan Company 22,168 (414 ) 21,754 Net Income Per Diluted Common Share Attributable to Stepan Company $ 0.95 $ (0.02 ) $ 0.93 (In thousands, except per share amounts) Nine Months Ended September 30, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Cost of Sales $ 1,264,223 $ (1,780 ) $ 1,262,443 Gross Profit 262,975 1,780 264,755 Operating Income 112,034 1,780 113,814 Income Before Provision for Income Taxes 105,404 1,780 107,184 Provision for Income Taxes 19,597 436 20,033 Net Income 85,807 1,344 87,151 Net Income Attributable to Stepan Company 85,816 1,344 87,160 Net Income Per Diluted Common Share Attributable to Stepan Company $ 3.68 $ 0.06 $ 3.74 Balance Sheet (In thousands) December 31, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Inventories $ 200,165 $ 31,363 $ 231,528 Other Non-Current Assets 10,964 (1,415 ) 9,549 Total Assets 1,484,666 29,948 1,514,614 Deferred Income Taxes $ 18,672 $ 6,289 $ 24,961 Retained Earnings 813,448 23,659 837,107 Total Liabilities and Equity 1,484,666 29,948 1,514,614 Statement of Cash Flows (In thousands) Nine Months Ended September 30, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Net Income $ 85,807 $ 1,344 $ 87,151 Deferred Income Taxes 6,410 436 6,846 Change in Assets and Liabilities: Inventories (21,586 ) (1,780 ) (23,366 ) The following tables present what current year financial statement line items would have been had the Company not changed its method of accounting for U.S. inventories from the LIFO to FIFO basis: Income Statement (In thousands, except per share amounts) Three Months Ended September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Cost of Sales $ 374,180 $ (1,000 ) $ 373,180 Gross Profit 77,402 1,000 78,402 Operating Income 27,966 1,000 28,966 Income Before Provision for Income Taxes 27,449 1,000 28,449 Provision for Income Taxes 1,569 246 1,815 Net Income 25,880 754 26,634 Net Income Attributable to Stepan Company 25,889 754 26,643 Net Income Per Diluted Common Share Attributable to Stepan Company $ 1.11 $ 0.03 $ 1.14 (In thousands, except per share amounts) Nine Months Ended September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Cost of Sales $ 1,158,785 $ (3,000 ) $ 1,155,785 Gross Profit 254,970 3,000 257,970 Operating Income 98,769 3,000 101,769 Income Before Provision for Income Taxes 98,013 3,000 101,013 Provision for Income Taxes 16,945 738 17,683 Net Income 81,068 2,262 83,330 Net Income Attributable to Stepan Company 81,091 2,262 83,353 Net Income Per Diluted Common Share Attributable to Stepan Company $ 3.48 $ 0.10 $ 3.58 Balance Sheet (In thousands) September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Inventories $ 203,303 $ (28,363 ) $ 174,940 Other Non-Current Assets 10,985 1,415 12,400 Total Assets 1,518,370 (26,948 ) 1,491,422 Deferred Income Taxes $ 25,218 $ (5,551 ) $ 19,667 Retained Earnings 906,612 (21,397 ) 885,215 Total Liabilities and Equity 1,518,370 (26,948 ) 1,491,422 Statement of Cash Flows (In thousands) Nine Months Ended September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Net Income $ 81,068 $ 2,262 $ 83,330 Deferred Income Taxes (2,291 ) 738 (1,553 ) Change in Assets and Liabilities: Inventories 25,879 (3,000 ) 22,879

Reconciliations of Equity

Reconciliations of Equity	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Reconciliations of Equity	3. RECONCILIATIONS OF EQUITY Below are reconciliations of total equity, Company equity and equity attributable to noncontrolling interests for the three and nine months ended September 30, 2019 and 2018: (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance at June 30, 2019 858,397 26,453 188,781 (106,202 ) (137,723 ) 886,349 739 Issuance of 13,256 shares of common stock under stock option plan 667 13 654 — — — — Purchase of 73,821 shares of common stock (7,003 ) — — (7,003 ) — — — Stock-based and deferred compensation 1,408 15 1,969 (576 ) — — — Net income 25,880 — — — — 25,889 (9 ) Other comprehensive income (18,816 ) — — — (18,784 ) — (32 ) Cash dividends paid: Common stock ($0.25 per share) (5,626 ) — — — — (5,626 ) — Balance at September 30, 2019 $ 854,907 $ 26,481 $ 191,404 $ (113,781 ) $ (156,507 ) $ 906,612 $ 698 (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance at December 31, 2018 (2) $ 808,185 $ 26,309 $ 182,881 $ (97,389 ) $ (141,483 ) $ 837,107 $ 760 Issuance of 56,385 shares of common stock under stock option plan 2,830 56 2,774 — — — — Purchase of 144,457 shares of common stock (13,184 ) — — (13,184 ) — — — Stock-based and deferred compensation 2,657 116 5,749 (3,208 ) — — — Net income 81,068 — — — — 81,091 (23 ) Other comprehensive income (9,738 ) — — — (9,699 ) — (39 ) Cash dividends paid: Common stock ($0.75 per share) (16,911 ) — — — — (16,911 ) — Other (3) — — — — (5,325 ) 5,325 — Balance at September 30, 2019 $ 854,907 $ 26,481 $ 191,404 $ (113,781 ) $ (156,507 ) $ 906,612 $ 698 (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance at June 30, 2018 (2) 789,096 26,279 177,779 (93,559 ) (124,290 ) 802,093 794 Issuance of 5,032 shares of common stock under stock option plan 214 5 209 — — — — Purchase of 16,833 shares of common stock (1,500 ) — — (1,500 ) — — — Stock-based and deferred compensation 2,311 3 2,380 (72 ) — — — Net income (2) 21,754 — — — — 21,754 — Other comprehensive income (1,748 ) — — — (1,717 ) — (31 ) Cash dividends paid: Common stock ($0.23 per share) (5,065 ) — — — — (5,065 ) — Balance at September 30, 2018 (2) $ 805,062 $ 26,287 $ 180,368 $ (95,131 ) $ (126,007 ) $ 818,782 $ 763 (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance, December 31, 2017 (2) $ 766,218 $ 26,071 $ 170,408 $ (78,561 ) $ (99,563 ) $ 747,045 $ 818 Issuance of 85,394 shares of common stock under stock option plan 3,488 85 3,403 — — — — Purchase of 156,524 shares of common stock (13,500 ) — — (13,500 ) — — — Stock-based and deferred compensation 3,618 131 6,557 (3,070 ) — — — Net income (2) 87,151 — — — — 87,160 (9 ) Other comprehensive income (26,490 ) — — — (26,444 ) — (46 ) Cash dividends paid: Common stock ($0.70 per share) (15,225 ) — — — — (15,225 ) — Other (4) (198 ) — — — — (198 ) — Balance at September 30, 2018 (2) $ 805,062 $ 26,287 $ 180,368 $ (95,131 ) $ (126,007 ) $ 818,782 $ 763 (1) (2) . (3) Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (4) Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	4 . FAIR VALUE MEASUREMENTS The following were the financial instruments held by the Company at September 30, 2019, and December 31, 2018, 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 include the foreign currency exchange contracts discussed in Note 5. 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 below that describes financial assets and liabilities measured on a recurring basis for the reported fair values of derivative assets and liabilities. Long-term investments Long-term investments include 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 10). 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 September 30, 2019, and December 31, 2018, 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 $789,000 and $978,000 as of September 30, 2019 and December 31, 2018, respectively): (In thousands) September 30, 2019 December 31, 2018 Fair value $ 237,766 $ 274,119 Carrying value 232,709 277,058 The following tables present financial assets and liabilities measured on a recurring basis at fair value as of September 30, 2019, and December 31, 2018, and the level within the fair value hierarchy in which the fair value measurements fall: (In thousands) September 30, 2019 Level 1 Level 2 Level 3 Mutual fund assets $ 26,389 $ 26,389 $ — $ — Derivative assets: Foreign currency contracts 91 — 91 — Total assets at fair value $ 26,480 $ 26,389 $ 91 $ — Derivative liabilities: Foreign currency contracts $ 280 $ — $ 280 $ — (In thousands) December 31, 2018 Level 1 Level 2 Level 3 Mutual fund assets $ 25,082 $ 25,082 $ — $ — Derivative assets: Foreign currency contracts 185 — 185 — Total assets at fair value $ 25,267 $ 25,082 $ 185 $ — Derivative liabilities: Foreign currency contracts $ 10 $ — $ 10 $ —

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2019
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Instruments	5 . 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 den ominated 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 September 30, 2019, and Dece mber 31, 2018, 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 $ 35,857,965 and $ 28,870,081 , respectively. The fair values of the derivative instruments held by the Company on September 30, 2019, and December 31, 2018, are disclosed in Note 4. Derivative instrument gains and losses for the three- and nine- month periods ended September 30, 2019 and 2018, were immaterial. For amounts reclassified out of accumulated other comprehensive income (loss) (AOCI) into earnings for the three- and nine- month periods ended September 30, 2019 and 2018, see Note 12.

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based Compensation	6 . STOCK-BASED COMPENSATION On September 30, 2019, the Company had 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 September 30 Nine Months Ended September 30 2019 2018 2019 2018 $ 2,273 $ 3,335 $ 7,045 $ 6,722 The quarter-over-quarter decrease in stock-based compensation expense was primarily attributable to cash-settled SARs. The cash-settled SARs compensation expense during the third quarter of 2019 was less than a year ago reflecting a smaller increase in the market value of Company stock during the third quarter of 2019 versus the increase during the third quarter of 2018. Unrecognized compensation costs for stock options, stock awards and SARs were as follows: (In thousands) September 30, 2019 December 31, 2018 Stock options $ 2,270 $ 1,655 Stock awards 4,114 3,180 SARs 4,964 3,566 The increases in unrecognized compensation costs for stock options, stock awards and SARs reflected the 2019 grants of: Shares Stock options 72,965 Stock awards (at target) 45,327 SARs 162,624 The unrecognized compensation costs at September 30, 2019, are expected to be recognized over weighted-average periods of 1.9 years, 1.8 years and 1.9 years for stock options, stock awards and SARs, respectively.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventories	7 . INVENTORIES The composition of inventories at September 30, 2019, and December 31, 2018, was as follows: (In thousands) September 30, 2019 December 31, 2018 As Adjusted Finished goods $ 148,320 $ 163,617 Raw materials 54,983 67,911 Total inventories $ 203,303 $ 231,528 Effective January 1, 2019, the Company elected to change its method of accounting for U.S. inventories from the LIFO basis to the FIFO basis. Non-U.S. inventories have historically been maintained on the FIFO basis. Prior period financial statements have been adjusted to reflect what results would have been had the Company always used the FIFO method of inventory valuation for U.S. inventories. See Note 2 for additional details.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	8. LEASES The Company adopted ASU No. 2016-02, Leases (Topic 842) Leases (Topic 842) The Company elected to apply the new lease standard at adoption as allowed under ASU No. 2018-11 and, as a result, the Company did not retrospectively adjust prior periods presented. The Company elected the practical expedient to not separate non-lease components from lease components for all asset classes and the practical expedient which permits a Company to not reassess prior conclusions about lease identification, lease classifications and initial direct costs. The Company did not elect the use-of-hindsight or the practical expedient pertaining to land easements, the latter not being applicable to the Company. In addition, the Company made an accounting policy election to keep leases with an initial term of 12 months or less off the balance sheet. Upon adoption of ASC 842, the Company recognized $42.4 Significant judgments used by the Company to determine whether a contract is or contains a lease include: (i) determining whether any explicitly or implicitly identified assets have been identified in the contract and (ii) determining whether the Company obtains substantially all of the economic benefits from the use of an underlying asset and directs how and for what purpose the asset is used during the term of the contract. The Company’s operating leases are primarily comprised of railcars, real estate, storage tanks, autos, trailers and manufacturing/office equipment. Railcars and real estate comprise approximately 50 percent and 37 percent, respectively, of the Company’s consolidated ROU asset balance. With the exception of real estate, typical lease terms range from one to ten years. Real estate lease terms typically range from one to fifty years. The Company’s two principal real estate leases relate to land leases in the Philippines and Singapore. As of September 30, 2019, the Company had additional leases, primarily for leases of real estate and railcars, that have not commenced of approximately $1.9 million. The majority of these leases will commence in the fourth quarter of 2019 with lease terms ranging from one to five years. Variability associated with the Company’s lease obligations typically relates to: (i) additional charges based on usage (i.e., railcar mileage in excess of a specified amount) and, (ii) periodic increases associated with Consumer Price Index (CPI) changes (i.e., land rental payments). Appropriate CPI at the inception of a lease is reflected in the Company’s lease liability balances whereas variability based on usage is typically excluded from lease liability amounts. Some of the Company’s leases include options to extend the lease term but these are typically not recognized as part of the ROU asset or lease liability at inception unless it is reasonably certain the renewal option will be exercised. Determining whether a renewal option is reasonably certain to be exercised requires judgment based on the existing facts and circumstances as well as expectations about future business needs. Renewal options are typically re-assessed within one year or less prior to lease termination when the Company is able to more accurately forecast future business needs. Some of the Company’s lease contracts include options to terminate leases early but these are typically not considered unless it is reasonably certain the early termination option will be exercised. The Company’s leases do not typically carry any residual value guarantees and typically payment is not considered probable when such guarantees are included in the contract. Initial implementation of ASU No. 2016-02, Leases (Topic 842) did not impact compliance with any of the Company’s debt covenants, nor is it expected to in the future. The majority of the Company’s debt agreements contain language that excludes the impact of any new GAAP accounting change. As most of the Company’s leases do not provide an implicit borrowing rate, the Company uses its incremental borrowing rate (IBR) based on the information available at the commencement date in determining the present value of lease payments. IBRs were specifically determined for the United States, the Philippines, Singapore and China, typically for five-year increments. The U.S. IBR was used for all other countries as the leases in these countries are not material. The total value of leases that reside in the four countries identified above represents approximately 94 percent of the Company’s consolidated ROU asset balance. (In thousands) Three months ended September 30, 2019 Nine months ended September 30, 2019 Lease Cost Operating lease cost $ 2,698 $ 8,097 Short-term lease cost 1,249 3,367 Variable lease cost 303 884 Total lease cost $ 4,250 $ 12,348 Other Information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flow from operating leases $ 2,718 $ 8,139 Right-of-use assets obtained in exchange for new operating lease liabilities 1,593 2,482 (In thousands) Undiscounted Cash Flows: 2019 (excluding the nine months ended September 30, 2019) $ 2,734 2020 9,771 2021 6,899 2022 5,699 2023 4,457 Subsequent to 2023 18,376 Total Undiscounted Cash Flows $ 47,936 Less: Imputed interest (9,899 ) Present value $ 38,037 Current operating lease liabilities (1) 8,973 Non-current operating lease liabilities 29,064 Total lease liabilities $ 38,037 (1) This item is included in Accrued liabilities line on the Company’s Condensed Consolidated Balance Sheet. Weighted-average remaining lease term-operating leases 9 Years Weighted-average discount rate-operating leases 4.3% ASC 840 Disclosure As required in transition, the table below summarizes the Company’s future minimum lease payments at December 31, 2018 under ASC 840. (In thousands) Year 2019 $ 9,740 2020 8,294 2021 6,027 2022 5,242 2023 4,101 Subsequent to 2023 16,593 Total minimum future rental payments $ 49,997

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Contingencies	9 . CONTINGENCIES There are a variety of legal proceedings pending or threatened against the Company that occur in the normal course of the Company’s business, the majority of which relate to environmental matters. 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 comparable regulations applicable to the Company’s foreign locations. Over the years, the Company has received requests for information related to or has been named by the government authorities as a potentially responsible party (PRP) at a number of 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. The Company believes that it has made adequate provisions for the costs it is likely to incur with respect to these sites. As of September 30, 2019, the Company estimated a range of possible environmental and legal losses of $23.9 million to $45.6 million. Within the range of possible environmental and legal losses, management has currently concluded that no single amount is more likely to occur than any other amounts in the ranges and, thus, has accrued at the lower end of the ranges; that accrual totaled $23.9 million at September 30, 2019 and $23.4 million at December 31, 2018. Cash expenditures related to legal and environmental matters approximated $2.8 million for the nine months ended September 30, 2019, compared to $1.0 million for the same period in 2018. 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. 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, management believes that the Company has no material liability at these sites and 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 September 30, 2019: 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 1993 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 the USEPA to the Company for property currently owned by the Company, the Company has completed various remedial investigation feasibility studies, and on September 24, 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 is reasonable having considered the range of estimated cost of remediation for the Maywood site. The 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 Comp any is liable could differ materially 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 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 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 is reasonable having considered the range of estimated 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 materially 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 $2.8 million for the Company’s portion of environmental response costs through September 30, 2019. 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 materially 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 of the affected areas is appropriate based on estimate of expected costs. However, actual costs could differ materially from current estimates.

Postretirement Benefit Plans

Postretirement Benefit Plans	9 Months Ended
	Sep. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Postretirement Benefit Plans	10 . 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 September 30 Nine Months Ended September 30 2019 2018 2019 2018 Interest cost $ 1,640 $ 1,566 $ 4,962 $ 4,645 Expected return on plan assets (2,365 ) (2,320 ) (7,087 ) (6,962 ) Amortization of net actuarial loss 563 987 1,867 2,860 Net periodic benefit cost $ (162 ) $ 233 $ (258 ) $ 543 UNITED KINGDOM (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Interest cost $ 134 $ 138 $ 416 $ 430 Expected return on plan assets (190 ) (216 ) (589 ) (673 ) Amortization of net actuarial loss 59 53 184 166 Net periodic benefit cost $ 3 $ (25 ) $ 11 $ (77 ) 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 2019. Of such amount, $256,000 had been paid related to the non-qualified plans as of September 30, 2019. U.K. Plan The Company’s U.K. subsidiary expects to contribute approximately $476,000 to its defined benefit pension plan in 2019. Of such amount, $408,000 had been contributed to the plan as of September 30, 2019. 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. In the nine months ended September 30, 2019 and 2018, the Company made profit sharing contributions into the qualified retirement plans for U.S. employees and for certain non-U.S. employees. Profit sharing contributions were determined using a formula applied to Company earnings. In 2018, for U.S. employees, who received the majority of profit sharing contributions, profit sharing contributions were made partly to the 401(k) plan and partly to the employee stock ownership plan and in 2019, profit sharing contributions were made to the employee stock ownership plan. Profit sharing contributions are allocated to participant accounts on the basis of participant base earnings. Defined contribution plan expenses for the Company’s qualified contribution plans were as follows: (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Retirement savings contributions $ 1,777 $ 1,738 $ 5,401 $ 5,201 Profit sharing contributions 567 759 2,413 2,769 Total $ 2,344 $ 2,497 $ 7,814 $ 7,970 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 s ame 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 r ecognized) 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 September 30, 2019, 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 4 for further information regarding the Company’s mutual fund assets).

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share	11 . EARNINGS PER SHARE Below are the computations of basic and diluted earnings per share for the three and nine months ended September 30, 2019 and 2018: (In thousands, except per share amounts) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 As Adjusted 2019 2018 As Adjusted Computation of Basic Earnings per Share Net income attributable to Stepan Company (1) $ 25,889 $ 21,754 $ 81,091 $ 87,160 Weighted-average number of common shares outstanding 23,025 22,986 23,070 23,036 Basic earnings per share (1) $ 1.12 $ 0.95 $ 3.52 $ 3.78 Computation of Diluted Earnings per Share Net income attributable to Stepan Company (1) $ 25,889 $ 21,754 $ 81,091 $ 87,160 Weighted-average number of shares outstanding 23,025 22,986 23,070 23,036 Add weighted-average net shares from assumed exercise of options (under treasury stock method) (2) 102 103 95 103 Add weighted-average net shares related to unvested stock awards (under treasury stock method) 1 3 2 2 Add weighted-average net shares from assumed exercise of SARs (under treasury stock method) (2) 135 113 120 111 Add weighted-average contingently issuable net shares related to performance stock awards (under treasury stock method) 37 83 33 72 Weighted-average shares applicable to diluted earnings 23,300 23,288 23,320 23,324 Diluted earnings per share (1) $ 1.11 $ 0.93 $ 3.48 $ 3.74 (1) The (2)

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	12. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) In conjunction with the adoption of ASU 2018-02, the Company reclassified $5,325,000 of other comprehensive loss, associated with retirement plans, from accumulated other comprehensive loss to retained earnings effective January 1, 2019. Below is the change in the Company’s AOCI balance by component (net of income taxes) for the three and nine months ended September 30, 2019 and 2018: (In thousands) Foreign Currency Translation Adjustments Defined Benefit Pension Plan Adjustments Cash Flow Hedge Adjustments Total Balance at June 30, 2018 $ (96,788 ) $ (27,588 ) $ 86 $ (124,290 ) Other comprehensive income before reclassifications (2,503 ) — — (2,503 ) Amounts reclassified from AOCI — 788 (2 ) 786 Net current-period other comprehensive income (2,503 ) 788 (2 ) (1,717 ) Balance at September 30, 2018 $ (99,291 ) $ (26,800 ) $ 84 $ (126,007 ) Balance at June 30, 2019 $ (100,477 ) $ (37,323 ) $ 77 $ (137,723 ) Other comprehensive income before reclassifications (19,255 ) — — (19,255 ) Amounts reclassified from AOCI — 473 (2 ) 471 Net current-period other comprehensive income (19,255 ) 473 (2 ) (18,784 ) Balance at September 30, 2019 $ (119,732 ) $ (36,850 ) $ 75 $ (156,507 ) Balance at December 31, 2017 $ (70,561 ) $ (29,093 ) $ 91 $ (99,563 ) Other comprehensive income before reclassifications (28,730 ) — — (28,730 ) Amounts reclassified from AOCI — 2,293 (7 ) 2,286 Net current-period other comprehensive income (28,730 ) 2,293 (7 ) (26,444 ) Balance at September 30, 2018 $ (99,291 ) $ (26,800 ) $ 84 $ (126,007 ) Balance at December 31, 2018 $ (108,481 ) $ (33,083 ) $ 81 $ (141,483 ) Other comprehensive income before reclassifications (11,251 ) — — (11,251 ) Amounts reclassified from AOCI — 1,558 (6 ) 1,552 Remeasurement adjustment related to the Tax Act (1) — (5,325 ) — (5,325 ) Net current-period other comprehensive income (11,251 ) (3,767 ) (6 ) (15,024 ) Balance at September 30, 2019 $ (119,732 ) $ (36,850 ) $ 75 $ (156,507 ) (1) Represents reclassification of the stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (Tax Act) from accumulated other comprehensive income (loss) to retained earnings in accordance with ASU 2018-02. See Note 19 for more details. Information regarding the reclassifications out of AOCI for the three and nine month periods ended September 30, 2019 and 2018, is displayed below: (In thousands) Amount Reclassified from AOCI (a) AOCI Components Three Months Ended September 30 Nine Months Ended September 30 Affected Line Item in Consolidated Statements of Income 2019 2018 2019 2018 Amortization of defined benefit pension actuarial losses $ (622 ) $ (1,040 ) $ (2,051 ) $ (3,026 ) (b) 149 252 493 733 Tax benefit $ (473 ) $ (788 ) $ (1,558 ) $ (2,293 ) Net of tax Gains and losses on cash flow hedges: Foreign exchange contracts 2 2 6 7 Cost of sales 2 2 6 7 Total before tax — — — — Tax benefit $ 2 $ 2 $ 6 $ 7 Net of tax Total reclassifications for the period $ (471 ) $ (786 ) $ (1,552 ) $ (2,286 ) 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 10 for additional details).

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Reporting	13. SEGMENT REPORTING The Company has three reportable segments: Surfactants, Polymers and Specialty Products. Net sales by segment for the three and nine months ended September 30, 2019 and 2018, were as follows: (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Segment Net Sales Surfactants $ 299,719 $ 346,884 $ 962,749 $ 1,062,708 Polymers 135,089 141,646 395,904 404,446 Specialty Products 16,774 19,467 55,102 60,044 Total $ 451,582 $ 507,997 $ 1,413,755 $ 1,527,198 Segment operating income and reconciliations of segment operating income to income before provision for income taxes for the three and nine months ended September 30, 2019 and 2018, are summarized below: (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 As Adjusted 2019 2018 As Adjusted Segment Operating Income Surfactants (1) $ 19,660 $ 28,824 $ 88,913 $ 104,370 Polymers (1) 23,283 19,259 58,148 56,863 Specialty Products 2,261 2,653 11,374 6,543 Segment operating income (1) 45,204 50,736 158,435 167,776 Business restructuring (459 ) (1,715 ) (1,642 ) (2,346 ) Unallocated corporate expenses (2) (16,779 ) (21,876 ) (58,024 ) (51,616 ) Consolidated operating income (1) 27,966 27,145 98,769 113,814 Interest expense, net (1,402 ) (2,797 ) (5,021 ) (8,620 ) Other, net 885 346 4,265 1,990 Income before provision for income taxes (1) $ 27,449 $ 24,694 $ 98,013 $ 107,184 (1) The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO . (2) 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 Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Revenue from Contracts with Customers	14. 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 a product is shipped and control passes to the customer. For a small portion of the business, performance obligations are deemed satisfied when product is delivered to a customer location. As of September 30, 2019, 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 provide a geographic disaggregation of net sales for the three and nine months ended September 30, 2019 and 2018. The Company’s business segmentation by geographic region most effectively captures the nature and economic characteristics of the Company’s revenue streams. For the Three Months Ended September 30, 2019 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 178,799 $ 84,397 $ 14,035 $ 277,231 Europe 57,190 39,852 2,739 99,781 Latin America 51,940 792 — 52,732 Asia 11,790 10,048 — 21,838 Total $ 299,719 $ 135,089 $ 16,774 $ 451,582 For the Three Months Ended September 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 205,032 $ 87,720 $ 16,877 $ 309,629 Europe 68,120 45,780 2,590 116,490 Latin America 58,560 978 — 59,538 Asia 15,172 7,168 — 22,340 Total $ 346,884 $ 141,646 $ 19,467 $ 507,997 For the Nine Months Ended September 30, 2019 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 584,816 $ 242,154 $ 46,127 $ 873,097 Europe 183,028 126,042 8,975 318,045 Latin America 156,709 2,439 — 159,148 Asia 38,196 25,269 — 63,465 Total $ 962,749 $ 395,904 $ 55,102 $ 1,413,755 For the Nine Months Ended September 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 643,466 $ 248,160 $ 50,365 $ 941,991 Europe 212,556 132,592 9,679 354,827 Latin America 156,827 2,438 — 159,265 Asia 49,859 21,256 — 71,115 Total $ 1,062,708 $ 404,446 $ 60,044 $ 1,527,198

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	15. DEBT At September 30, 2019, and December 31, 2018, debt comprised the following: (In thousands) Maturity Dates September 30, 2019 December 31, 2018 Unsecured private placement notes 3.95% (net of unamortized debt issuance cost of $327 and $360 for 2019 and 2018, respectively) 2021-2027 $ 99,673 $ 99,640 3.86% (net of unamortized debt issuance cost of $305 and $347 for 2019 and 2018, respectively) 2019-2025 85,409 99,653 4.86% (net of unamortized debt issuance cost of $157 and $186 for 2019 and 2018, respectively) 2019-2023 46,271 46,243 5.88% (net of unamortized debt issuance cost of $0 and $85 for 2019 and 2018, respectively) 2019-2022 — 22,772 Debt of foreign subsidiaries Unsecured bank debt, foreign currency 2019 567 7,772 Total debt $ 231,920 $ 276,080 Less current maturities 24,137 37,058 Long-term debt $ 207,783 $ 239,022 The Company has a committed $350,000,000 multi-currency revolving credit agreement that expires on January 30, 2023. 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 September 30, 2019, the Company had outstanding letters of credit totaling $5,009,000 and no outstanding debt under this agreement. There was $344,991,000 available under the revolving credit agreement as of September 30, 2019. 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 $267,903,000 and $214,101,000 at September 30, 2019 and December 31, 2018, respectively. On June 12, 2019, the Company prepaid the $17,100,000 outstanding principal balance of its 5.88 percent Series 2010-A Senior Notes due June 1, 2022 (Notes) and the related make-whole amount of $1,173,000. The make-whole amount reflected the net present value of the remaining scheduled interest payments on the Notes, calculated in accordance with the applicable note purchase agreement. The prepayment was made with cash on hand. The Company also expensed remaining unamortized debt issuance costs of $74,000.

Other, Net

Other, Net	9 Months Ended
	Sep. 30, 2019
Other Income And Expenses [Abstract]
Other, Net	16. OTHER, NET Other, net in the consolidated statements of income included the following: (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Foreign exchange gain (loss) $ 374 $ (274 ) $ 333 $ 895 Investment income 106 91 309 320 Realized and unrealized gain (loss) on investments (324 ) 737 2,806 1,241 Net periodic pension benefit cost 159 (208 ) 247 (466 ) Gain on sale of asset 570 — 570 — Other, net $ 885 $ 346 $ 4,265 $ 1,990

Business Restructuring

Business Restructuring	9 Months Ended
	Sep. 30, 2019
Restructuring And Related Activities [Abstract]
Business Restructuring	17. BUSINESS RESTRUCTURING In the first quarter of 2019, the Company approved a plan to restructure its Specialty Products office in the Netherlands and eliminate five positions from the site’s supply chain, quality control and research and development areas. This restructuring was designed to better align the number of personnel with current business requirements and reduce costs at the site. As a result, severance and early lease termination expenses of $396,000 and $122,000, respectively, were recognized during the nine months ended September 30, 2019. During the third quarter of 2018, the Company approved a plan to shut down Surfactant operations at its German plant site. As of September 30, 2019, an aggregate of $1,968,000 shut down related expense had been recognized at the site. This aggregate expense is comprised of $1,404,000 of asset and spare part write downs recognized in 2018 and $564,000 of decommissioning costs recognized in the nine months ended September 30, 2019. Decommissioning costs associated with the shutdown are expected to continue throughout the remainder of 2019. In the fourth quarter of 2017, the Company approved a plan to restructure a portion of its Fieldsboro, New Jersey production facility. This facility is a part of the Surfactant reportable segment. As a result, the Company recorded $915,000 of restructuring expense which reflected termination benefits for select plant employees. In the first quarter of 2019, the Company recognized a $251,000 favorable adjustment to the amount of termination benefits initially recorded. 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 implemented 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 North American production sites. Decommissioning of the assets is expected to continue throughout 2019. In the third quarter of 2019, the Company recognized $290,000 of decommissioning expenses. As of September 30, 2019, $6,885,000 of aggregate restructuring expense had been recognized, reflecting $1,644,000 of termination benefits for approximately 30 employees and $5,241,000 for other expenses, principally site decommissioning costs.

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Acquisition	18. ACQUISITION 2018 Acquisition On March 26, 2018, the Company through a subsidiary in Mexico closed on a previously announced agreement with BASF Mexicana, S.A.DE C.V. (BASF) to acquire their surfactants production facility in Ecatepec, Mexico and a portion of their associated surfactants business. The facility is located close to Mexico City and 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 $22,852,000 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. No intangible assets were identified as part of the acquisition. The following table summarizes the assets acquired as a result of the acquisition: (In thousands) Assets: Property, plant and equipment $ 14,464 Inventory 5,687 Value-added tax receivables 2,701 Total assets acquired $ 22,852 The acquired business had minimal impact on the Company’s 2018 financial results.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2019
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	19. RECENT ACCOUNTING PRONOUNCEMENTS In February 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-2, Leases (Topic 842) Leases (Topic 842) Leases 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, Accumulated Other Comprehensive Income (Loss) In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In January 2017, the FASB issued ASU No. 2017-4, Intang ibles – Goodwill and Other (Topic 350) : Simplifying the Test for Goodwill Impairment , which eliminates Step 2 from the goodwill impairment test. When an indication of impairment was identified after performing the first step of the goodwill impairment test , Step 2 required that an entity determine the fair value at the impairment testing date of its assets and liabilities (including unrecognized assets and liabilities) using the same procedure that would be required in determining the fair value of assets a cquired and liabilities assumed in a business combination. Under the amendments in ASU No. 2017-4, an entity would perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying value. An entity w ould recognize an impairment charge for the amount by which the carrying value exceeds the reporting unit’s fair value. In addition, an entity must consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit wh en measuring the goodwill impairment loss, if applicable. The Company is required to adopt the amendments in ASU No. 2017-4 for its annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019. It is not expected that the adoption of the guidance in ASU No. 2017-4 will have a material effect on the Company’s financial position, results of operations or cash flows. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20) In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	In February 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-2, Leases (Topic 842) Leases (Topic 842) Leases 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, Accumulated Other Comprehensive Income (Loss) In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In January 2017, the FASB issued ASU No. 2017-4, Intang ibles – Goodwill and Other (Topic 350) : Simplifying the Test for Goodwill Impairment , which eliminates Step 2 from the goodwill impairment test. When an indication of impairment was identified after performing the first step of the goodwill impairment test , Step 2 required that an entity determine the fair value at the impairment testing date of its assets and liabilities (including unrecognized assets and liabilities) using the same procedure that would be required in determining the fair value of assets a cquired and liabilities assumed in a business combination. Under the amendments in ASU No. 2017-4, an entity would perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying value. An entity w ould recognize an impairment charge for the amount by which the carrying value exceeds the reporting unit’s fair value. In addition, an entity must consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit wh en measuring the goodwill impairment loss, if applicable. The Company is required to adopt the amendments in ASU No. 2017-4 for its annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019. It is not expected that the adoption of the guidance in ASU No. 2017-4 will have a material effect on the Company’s financial position, results of operations or cash flows. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20) In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract

Change In Method of Accountin_2

Change In Method of Accounting for Inventory Valuation (Tables)	9 Months Ended
	Sep. 30, 2019
Change In Accounting Estimate [Abstract]
Summary of Prior Year Financial Statement Line Items that have Been Affected by Retrospective Change in Accounting Principle	The following tables present the prior year financial statement line items that have been affected by the retrospective change in accounting principle: Income Statement (In thousands, except per share amounts) Three Months Ended September 30, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Cost of Sales $ 423,872 $ 549 $ 424,421 Gross Profit 84,125 (549 ) 83,576 Operating Income 27,694 (549 ) 27,145 Income Before Provision for Income Taxes 25,243 (549 ) 24,694 Provision for Income Taxes 3,075 (135 ) 2,940 Net Income 22,168 (414 ) 21,754 Net Income Attributable to Stepan Company 22,168 (414 ) 21,754 Net Income Per Diluted Common Share Attributable to Stepan Company $ 0.95 $ (0.02 ) $ 0.93 (In thousands, except per share amounts) Nine Months Ended September 30, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Cost of Sales $ 1,264,223 $ (1,780 ) $ 1,262,443 Gross Profit 262,975 1,780 264,755 Operating Income 112,034 1,780 113,814 Income Before Provision for Income Taxes 105,404 1,780 107,184 Provision for Income Taxes 19,597 436 20,033 Net Income 85,807 1,344 87,151 Net Income Attributable to Stepan Company 85,816 1,344 87,160 Net Income Per Diluted Common Share Attributable to Stepan Company $ 3.68 $ 0.06 $ 3.74 Balance Sheet (In thousands) December 31, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Inventories $ 200,165 $ 31,363 $ 231,528 Other Non-Current Assets 10,964 (1,415 ) 9,549 Total Assets 1,484,666 29,948 1,514,614 Deferred Income Taxes $ 18,672 $ 6,289 $ 24,961 Retained Earnings 813,448 23,659 837,107 Total Liabilities and Equity 1,484,666 29,948 1,514,614 Statement of Cash Flows (In thousands) Nine Months Ended September 30, 2018 As originally reported under LIFO Effect of change As adjusted under FIFO Net Income $ 85,807 $ 1,344 $ 87,151 Deferred Income Taxes 6,410 436 6,846 Change in Assets and Liabilities: Inventories (21,586 ) (1,780 ) (23,366 )
Summary of Current Year Financial Statement Line Items If Company Does Not Changed Method of Accounting for U.S. Inventories from LIFO to FIFO	The following tables present what current year financial statement line items would have been had the Company not changed its method of accounting for U.S. inventories from the LIFO to FIFO basis: Income Statement (In thousands, except per share amounts) Three Months Ended September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Cost of Sales $ 374,180 $ (1,000 ) $ 373,180 Gross Profit 77,402 1,000 78,402 Operating Income 27,966 1,000 28,966 Income Before Provision for Income Taxes 27,449 1,000 28,449 Provision for Income Taxes 1,569 246 1,815 Net Income 25,880 754 26,634 Net Income Attributable to Stepan Company 25,889 754 26,643 Net Income Per Diluted Common Share Attributable to Stepan Company $ 1.11 $ 0.03 $ 1.14 (In thousands, except per share amounts) Nine Months Ended September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Cost of Sales $ 1,158,785 $ (3,000 ) $ 1,155,785 Gross Profit 254,970 3,000 257,970 Operating Income 98,769 3,000 101,769 Income Before Provision for Income Taxes 98,013 3,000 101,013 Provision for Income Taxes 16,945 738 17,683 Net Income 81,068 2,262 83,330 Net Income Attributable to Stepan Company 81,091 2,262 83,353 Net Income Per Diluted Common Share Attributable to Stepan Company $ 3.48 $ 0.10 $ 3.58 Balance Sheet (In thousands) September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Inventories $ 203,303 $ (28,363 ) $ 174,940 Other Non-Current Assets 10,985 1,415 12,400 Total Assets 1,518,370 (26,948 ) 1,491,422 Deferred Income Taxes $ 25,218 $ (5,551 ) $ 19,667 Retained Earnings 906,612 (21,397 ) 885,215 Total Liabilities and Equity 1,518,370 (26,948 ) 1,491,422 Statement of Cash Flows (In thousands) Nine Months Ended September 30, 2019 As reported under FIFO Effect of change As computed under LIFO Net Income $ 81,068 $ 2,262 $ 83,330 Deferred Income Taxes (2,291 ) 738 (1,553 ) Change in Assets and Liabilities: Inventories 25,879 (3,000 ) 22,879

Reconciliations of Equity (Tabl

Reconciliations of Equity (Tables)	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Reconciliations of Total Equity	Below are reconciliations of total equity, Company equity and equity attributable to noncontrolling interests for the three and nine months ended September 30, 2019 and 2018: (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance at June 30, 2019 858,397 26,453 188,781 (106,202 ) (137,723 ) 886,349 739 Issuance of 13,256 shares of common stock under stock option plan 667 13 654 — — — — Purchase of 73,821 shares of common stock (7,003 ) — — (7,003 ) — — — Stock-based and deferred compensation 1,408 15 1,969 (576 ) — — — Net income 25,880 — — — — 25,889 (9 ) Other comprehensive income (18,816 ) — — — (18,784 ) — (32 ) Cash dividends paid: Common stock ($0.25 per share) (5,626 ) — — — — (5,626 ) — Balance at September 30, 2019 $ 854,907 $ 26,481 $ 191,404 $ (113,781 ) $ (156,507 ) $ 906,612 $ 698 (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance at December 31, 2018 (2) $ 808,185 $ 26,309 $ 182,881 $ (97,389 ) $ (141,483 ) $ 837,107 $ 760 Issuance of 56,385 shares of common stock under stock option plan 2,830 56 2,774 — — — — Purchase of 144,457 shares of common stock (13,184 ) — — (13,184 ) — — — Stock-based and deferred compensation 2,657 116 5,749 (3,208 ) — — — Net income 81,068 — — — — 81,091 (23 ) Other comprehensive income (9,738 ) — — — (9,699 ) — (39 ) Cash dividends paid: Common stock ($0.75 per share) (16,911 ) — — — — (16,911 ) — Other (3) — — — — (5,325 ) 5,325 — Balance at September 30, 2019 $ 854,907 $ 26,481 $ 191,404 $ (113,781 ) $ (156,507 ) $ 906,612 $ 698 (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance at June 30, 2018 (2) 789,096 26,279 177,779 (93,559 ) (124,290 ) 802,093 794 Issuance of 5,032 shares of common stock under stock option plan 214 5 209 — — — — Purchase of 16,833 shares of common stock (1,500 ) — — (1,500 ) — — — Stock-based and deferred compensation 2,311 3 2,380 (72 ) — — — Net income (2) 21,754 — — — — 21,754 — Other comprehensive income (1,748 ) — — — (1,717 ) — (31 ) Cash dividends paid: Common stock ($0.23 per share) (5,065 ) — — — — (5,065 ) — Balance at September 30, 2018 (2) $ 805,062 $ 26,287 $ 180,368 $ (95,131 ) $ (126,007 ) $ 818,782 $ 763 (In thousands, except share and per share amounts) Total Common Stock Additional Paid-in Capital Treasury Stock Accumulated Other Comprehensive Income (Loss) Retained Earnings Noncontrolling Interest (1) Balance, December 31, 2017 (2) $ 766,218 $ 26,071 $ 170,408 $ (78,561 ) $ (99,563 ) $ 747,045 $ 818 Issuance of 85,394 shares of common stock under stock option plan 3,488 85 3,403 — — — — Purchase of 156,524 shares of common stock (13,500 ) — — (13,500 ) — — — Stock-based and deferred compensation 3,618 131 6,557 (3,070 ) — — — Net income (2) 87,151 — — — — 87,160 (9 ) Other comprehensive income (26,490 ) — — — (26,444 ) — (46 ) Cash dividends paid: Common stock ($0.70 per share) (15,225 ) — — — — (15,225 ) — Other (4) (198 ) — — — — (198 ) — Balance at September 30, 2018 (2) $ 805,062 $ 26,287 $ 180,368 $ (95,131 ) $ (126,007 ) $ 818,782 $ 763 (1) (2) . (3) Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (4) Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Values and Related Carrying Values of Debt	At September 30, 2019, and December 31, 2018, 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 $789,000 and $978,000 as of September 30, 2019 and December 31, 2018, respectively): (In thousands) September 30, 2019 December 31, 2018 Fair value $ 237,766 $ 274,119 Carrying value 232,709 277,058
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 September 30, 2019, and December 31, 2018, and the level within the fair value hierarchy in which the fair value measurements fall: (In thousands) September 30, 2019 Level 1 Level 2 Level 3 Mutual fund assets $ 26,389 $ 26,389 $ — $ — Derivative assets: Foreign currency contracts 91 — 91 — Total assets at fair value $ 26,480 $ 26,389 $ 91 $ — Derivative liabilities: Foreign currency contracts $ 280 $ — $ 280 $ — (In thousands) December 31, 2018 Level 1 Level 2 Level 3 Mutual fund assets $ 25,082 $ 25,082 $ — $ — Derivative assets: Foreign currency contracts 185 — 185 — Total assets at fair value $ 25,267 $ 25,082 $ 185 $ — Derivative liabilities: Foreign currency contracts $ 10 $ — $ 10 $ —

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
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 September 30 Nine Months Ended September 30 2019 2018 2019 2018 $ 2,273 $ 3,335 $ 7,045 $ 6,722
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) September 30, 2019 December 31, 2018 Stock options $ 2,270 $ 1,655 Stock awards 4,114 3,180 SARs 4,964 3,566
Share Based Payment Awards Granted in Period	The increases in unrecognized compensation costs for stock options, stock awards and SARs reflected the 2019 grants of: Shares Stock options 72,965 Stock awards (at target) 45,327 SARs 162,624

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Composition of Inventories	The composition of inventories at September 30, 2019, and December 31, 2018, was as follows: (In thousands) September 30, 2019 December 31, 2018 As Adjusted Finished goods $ 148,320 $ 163,617 Raw materials 54,983 67,911 Total inventories $ 203,303 $ 231,528

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule of Lease Cost and Other Information	(In thousands) Three months ended September 30, 2019 Nine months ended September 30, 2019 Lease Cost Operating lease cost $ 2,698 $ 8,097 Short-term lease cost 1,249 3,367 Variable lease cost 303 884 Total lease cost $ 4,250 $ 12,348 Other Information Cash paid for amounts included in the measurement of lease liabilities: Operating cash flow from operating leases $ 2,718 $ 8,139 Right-of-use assets obtained in exchange for new operating lease liabilities 1,593 2,482
Schedule of Lease Liability Payments	(In thousands) Undiscounted Cash Flows: 2019 (excluding the nine months ended September 30, 2019) $ 2,734 2020 9,771 2021 6,899 2022 5,699 2023 4,457 Subsequent to 2023 18,376 Total Undiscounted Cash Flows $ 47,936 Less: Imputed interest (9,899 ) Present value $ 38,037 Current operating lease liabilities (1) 8,973 Non-current operating lease liabilities 29,064 Total lease liabilities $ 38,037 (1) This item is included in Accrued liabilities line on the Company’s Condensed Consolidated Balance Sheet.
Schedule of Operating Leases Weighted Average, Remaining Lease Term and Discount Rate	Weighted-average remaining lease term-operating leases 9 Years Weighted-average discount rate-operating leases 4.3%
Schedule of Future Minimum Lease Payments Under ASC 840	As required in transition, the table below summarizes the Company’s future minimum lease payments at December 31, 2018 under ASC 840. (In thousands) Year 2019 $ 9,740 2020 8,294 2021 6,027 2022 5,242 2023 4,101 Subsequent to 2023 16,593 Total minimum future rental payments $ 49,997

Postretirement Benefit Plans (T

Postretirement Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost UNITED STATES (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Interest cost $ 1,640 $ 1,566 $ 4,962 $ 4,645 Expected return on plan assets (2,365 ) (2,320 ) (7,087 ) (6,962 ) Amortization of net actuarial loss 563 987 1,867 2,860 Net periodic benefit cost $ (162 ) $ 233 $ (258 ) $ 543 UNITED KINGDOM (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Interest cost $ 134 $ 138 $ 416 $ 430 Expected return on plan assets (190 ) (216 ) (589 ) (673 ) Amortization of net actuarial loss 59 53 184 166 Net periodic benefit cost $ 3 $ (25 ) $ 11 $ (77 )
Defined Contribution Plan Expenses for Company's Qualified Contribution Plans	Defined contribution plan expenses for the Company’s qualified contribution plans were as follows: (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Retirement savings contributions $ 1,777 $ 1,738 $ 5,401 $ 5,201 Profit sharing contributions 567 759 2,413 2,769 Total $ 2,344 $ 2,497 $ 7,814 $ 7,970

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
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 nine months ended September 30, 2019 and 2018: (In thousands, except per share amounts) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 As Adjusted 2019 2018 As Adjusted Computation of Basic Earnings per Share Net income attributable to Stepan Company (1) $ 25,889 $ 21,754 $ 81,091 $ 87,160 Weighted-average number of common shares outstanding 23,025 22,986 23,070 23,036 Basic earnings per share (1) $ 1.12 $ 0.95 $ 3.52 $ 3.78 Computation of Diluted Earnings per Share Net income attributable to Stepan Company (1) $ 25,889 $ 21,754 $ 81,091 $ 87,160 Weighted-average number of shares outstanding 23,025 22,986 23,070 23,036 Add weighted-average net shares from assumed exercise of options (under treasury stock method) (2) 102 103 95 103 Add weighted-average net shares related to unvested stock awards (under treasury stock method) 1 3 2 2 Add weighted-average net shares from assumed exercise of SARs (under treasury stock method) (2) 135 113 120 111 Add weighted-average contingently issuable net shares related to performance stock awards (under treasury stock method) 37 83 33 72 Weighted-average shares applicable to diluted earnings 23,300 23,288 23,320 23,324 Diluted earnings per share (1) $ 1.11 $ 0.93 $ 3.48 $ 3.74 (1) The (2)

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income	In conjunction with the adoption of ASU 2018-02, the Company reclassified $5,325,000 of other comprehensive loss, associated with retirement plans, from accumulated other comprehensive loss to retained earnings effective January 1, 2019. Below is the change in the Company’s AOCI balance by component (net of income taxes) for the three and nine months ended September 30, 2019 and 2018: (In thousands) Foreign Currency Translation Adjustments Defined Benefit Pension Plan Adjustments Cash Flow Hedge Adjustments Total Balance at June 30, 2018 $ (96,788 ) $ (27,588 ) $ 86 $ (124,290 ) Other comprehensive income before reclassifications (2,503 ) — — (2,503 ) Amounts reclassified from AOCI — 788 (2 ) 786 Net current-period other comprehensive income (2,503 ) 788 (2 ) (1,717 ) Balance at September 30, 2018 $ (99,291 ) $ (26,800 ) $ 84 $ (126,007 ) Balance at June 30, 2019 $ (100,477 ) $ (37,323 ) $ 77 $ (137,723 ) Other comprehensive income before reclassifications (19,255 ) — — (19,255 ) Amounts reclassified from AOCI — 473 (2 ) 471 Net current-period other comprehensive income (19,255 ) 473 (2 ) (18,784 ) Balance at September 30, 2019 $ (119,732 ) $ (36,850 ) $ 75 $ (156,507 ) Balance at December 31, 2017 $ (70,561 ) $ (29,093 ) $ 91 $ (99,563 ) Other comprehensive income before reclassifications (28,730 ) — — (28,730 ) Amounts reclassified from AOCI — 2,293 (7 ) 2,286 Net current-period other comprehensive income (28,730 ) 2,293 (7 ) (26,444 ) Balance at September 30, 2018 $ (99,291 ) $ (26,800 ) $ 84 $ (126,007 ) Balance at December 31, 2018 $ (108,481 ) $ (33,083 ) $ 81 $ (141,483 ) Other comprehensive income before reclassifications (11,251 ) — — (11,251 ) Amounts reclassified from AOCI — 1,558 (6 ) 1,552 Remeasurement adjustment related to the Tax Act (1) — (5,325 ) — (5,325 ) Net current-period other comprehensive income (11,251 ) (3,767 ) (6 ) (15,024 ) Balance at September 30, 2019 $ (119,732 ) $ (36,850 ) $ 75 $ (156,507 ) (1) Represents reclassification of the stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (Tax Act) from accumulated other comprehensive income (loss) to retained earnings in accordance with ASU 2018-02. See Note 19 for more details.
Summary of Amounts Reclassifications Out of Accumulated Other Comprehensive Income	Information regarding the reclassifications out of AOCI for the three and nine month periods ended September 30, 2019 and 2018, is displayed below: (In thousands) Amount Reclassified from AOCI (a) AOCI Components Three Months Ended September 30 Nine Months Ended September 30 Affected Line Item in Consolidated Statements of Income 2019 2018 2019 2018 Amortization of defined benefit pension actuarial losses $ (622 ) $ (1,040 ) $ (2,051 ) $ (3,026 ) (b) 149 252 493 733 Tax benefit $ (473 ) $ (788 ) $ (1,558 ) $ (2,293 ) Net of tax Gains and losses on cash flow hedges: Foreign exchange contracts 2 2 6 7 Cost of sales 2 2 6 7 Total before tax — — — — Tax benefit $ 2 $ 2 $ 6 $ 7 Net of tax Total reclassifications for the period $ (471 ) $ (786 ) $ (1,552 ) $ (2,286 ) 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 10 for additional details).

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Operating Segment	The Company has three reportable segments: Surfactants, Polymers and Specialty Products. Net sales by segment for the three and nine months ended September 30, 2019 and 2018, were as follows: (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 2019 2018 Segment Net Sales Surfactants $ 299,719 $ 346,884 $ 962,749 $ 1,062,708 Polymers 135,089 141,646 395,904 404,446 Specialty Products 16,774 19,467 55,102 60,044 Total $ 451,582 $ 507,997 $ 1,413,755 $ 1,527,198
Reconciliation of Segment Information to Income Before Provision for Income Taxes	Segment operating income and reconciliations of segment operating income to income before provision for income taxes for the three and nine months ended September 30, 2019 and 2018, are summarized below: (In thousands) Three Months Ended September 30 Nine Months Ended September 30 2019 2018 As Adjusted 2019 2018 As Adjusted Segment Operating Income Surfactants (1) $ 19,660 $ 28,824 $ 88,913 $ 104,370 Polymers (1) 23,283 19,259 58,148 56,863 Specialty Products 2,261 2,653 11,374 6,543 Segment operating income (1) 45,204 50,736 158,435 167,776 Business restructuring (459 ) (1,715 ) (1,642 ) (2,346 ) Unallocated corporate expenses (2) (16,779 ) (21,876 ) (58,024 ) (51,616 ) Consolidated operating income (1) 27,966 27,145 98,769 113,814 Interest expense, net (1,402 ) (2,797 ) (5,021 ) (8,620 ) Other, net 885 346 4,265 1,990 Income before provision for income taxes (1) $ 27,449 $ 24,694 $ 98,013 $ 107,184 (1) The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO . (2) 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 C_2

Revenue from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Geographic Disaggregation of Net Sales	The tables below provide a geographic disaggregation of net sales for the three and nine months ended September 30, 2019 and 2018. The Company’s business segmentation by geographic region most effectively captures the nature and economic characteristics of the Company’s revenue streams. For the Three Months Ended September 30, 2019 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 178,799 $ 84,397 $ 14,035 $ 277,231 Europe 57,190 39,852 2,739 99,781 Latin America 51,940 792 — 52,732 Asia 11,790 10,048 — 21,838 Total $ 299,719 $ 135,089 $ 16,774 $ 451,582 For the Three Months Ended September 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 205,032 $ 87,720 $ 16,877 $ 309,629 Europe 68,120 45,780 2,590 116,490 Latin America 58,560 978 — 59,538 Asia 15,172 7,168 — 22,340 Total $ 346,884 $ 141,646 $ 19,467 $ 507,997 For the Nine Months Ended September 30, 2019 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 584,816 $ 242,154 $ 46,127 $ 873,097 Europe 183,028 126,042 8,975 318,045 Latin America 156,709 2,439 — 159,148 Asia 38,196 25,269 — 63,465 Total $ 962,749 $ 395,904 $ 55,102 $ 1,413,755 For the Nine Months Ended September 30, 2018 (In thousands) Surfactants Polymers Specialty Products Total Geographic Market North America $ 643,466 $ 248,160 $ 50,365 $ 941,991 Europe 212,556 132,592 9,679 354,827 Latin America 156,827 2,438 — 159,265 Asia 49,859 21,256 — 71,115 Total $ 1,062,708 $ 404,446 $ 60,044 $ 1,527,198

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	At September 30, 2019, and December 31, 2018, debt comprised the following: (In thousands) Maturity Dates September 30, 2019 December 31, 2018 Unsecured private placement notes 3.95% (net of unamortized debt issuance cost of $327 and $360 for 2019 and 2018, respectively) 2021-2027 $ 99,673 $ 99,640 3.86% (net of unamortized debt issuance cost of $305 and $347 for 2019 and 2018, respectively) 2019-2025 85,409 99,653 4.86% (net of unamortized debt issuance cost of $157 and $186 for 2019 and 2018, respectively) 2019-2023 46,271 46,243 5.88% (net of unamortized debt issuance cost of $0 and $85 for 2019 and 2018, respectively) 2019-2022 — 22,772 Debt of foreign subsidiaries Unsecured bank debt, foreign currency 2019 567 7,772 Total debt $ 231,920 $ 276,080 Less current maturities 24,137 37,058 Long-term debt $ 207,783 $ 239,022

Other, Net (Tables)

Other, Net (Tables)	9 Months Ended
	Sep. 30, 2019
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 September 30 Nine Months Ended September 30 2019 2018 2019 2018 Foreign exchange gain (loss) $ 374 $ (274 ) $ 333 $ 895 Investment income 106 91 309 320 Realized and unrealized gain (loss) on investments (324 ) 737 2,806 1,241 Net periodic pension benefit cost 159 (208 ) 247 (466 ) Gain on sale of asset 570 — 570 — Other, net $ 885 $ 346 $ 4,265 $ 1,990

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
	Sep. 30, 2019
2018 Acquisition [Member]
Summary of Assets Acquired	The following table summarizes the assets acquired as a result of the acquisition: (In thousands) Assets: Property, plant and equipment $ 14,464 Inventory 5,687 Value-added tax receivables 2,701 Total assets acquired $ 22,852

Change in Method of Accountin_3

Change in Method of Accounting for Inventory Valuation - Additional Information (Detail) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Change In Accounting Estimate [Line Items]
Percentage of LIFO inventory			68.00%
Retained earnings	[1],[2]	$ 906,612	$ 837,107
Effect of Change [Member]
Change In Accounting Estimate [Line Items]
Retained earnings		$ (21,397)	$ 23,659
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The 2019 amounts for the noted line items include an adjustment related to the Company’s first quarter 2019 adoption of ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

Change in Method of Accountin_4

Change in Method of Accounting for Inventory Valuation - Summary of Prior Year Financial Statement Line Items that have Been Affected by Retrospective Change in Accounting Principle (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018		Dec. 31, 2018
Income Statement [Abstract]
Cost of Sales	[1]	$ 374,180	$ 424,421		$ 1,158,785	$ 1,262,443
Gross Profit	[1]	77,402	83,576		254,970	264,755
Operating Income	[1],[2]	27,966	27,145		98,769	113,814
Income Before Provision for Income Taxes	[1],[2]	27,449	24,694		98,013	107,184
Provision for Income Taxes	[1]	1,569	2,940		16,945	20,033
Net Income	[1],[2]	25,880	21,754	[3]	81,068	87,151	[3]
Net Income Attributable to Stepan Company	[1],[2]	$ 25,889	$ 21,754		$ 81,091	$ 87,160
Net Income Per Diluted Common Share Attributable to Stepan Company	[1],[2]	$ 1.11	$ 0.93		$ 3.48	$ 3.74
Balance Sheet [Abstract]
Inventories	[2]	$ 203,303			$ 203,303			$ 231,528
Other Non-Current Assets	[2]	10,985			10,985			9,549
Total Assets	[2]	1,518,370			1,518,370			1,514,614
Deferred Income Taxes	[2]	25,218			25,218			24,961
Retained Earnings	[2],[4]	906,612			906,612			837,107
Total Liabilities and Equity	[2]	1,518,370			1,518,370			1,514,614
Statement of Cash Flows [Abstract]
Net Income	[1],[2]	25,880	$ 21,754	[3]	81,068	$ 87,151	[3]
Deferred Income Taxes	[2]				(2,291)	6,846
Changes in assets and liabilities:
Inventories	[2]				25,879	(23,366)
As Originally Reported Under LIFO [Member]
Income Statement [Abstract]
Cost of Sales			423,872			1,264,223
Gross Profit			84,125			262,975
Operating Income			27,694			112,034
Income Before Provision for Income Taxes			25,243			105,404
Provision for Income Taxes			3,075			19,597
Net Income			22,168			85,807
Net Income Attributable to Stepan Company			$ 22,168			$ 85,816
Net Income Per Diluted Common Share Attributable to Stepan Company			$ 0.95			$ 3.68
Balance Sheet [Abstract]
Inventories								200,165
Other Non-Current Assets								10,964
Total Assets								1,484,666
Deferred Income Taxes								18,672
Retained Earnings								813,448
Total Liabilities and Equity								1,484,666
Statement of Cash Flows [Abstract]
Net Income			$ 22,168			$ 85,807
Deferred Income Taxes						6,410
Changes in assets and liabilities:
Inventories						(21,586)
Effect of Change [Member]
Income Statement [Abstract]
Cost of Sales		(1,000)	549		(3,000)	(1,780)
Gross Profit		1,000	(549)		3,000	1,780
Operating Income		1,000	(549)		3,000	1,780
Income Before Provision for Income Taxes		1,000	(549)		3,000	1,780
Provision for Income Taxes		246	(135)		738	436
Net Income		754	(414)		2,262	1,344
Net Income Attributable to Stepan Company		$ 754	$ (414)		$ 2,262	$ 1,344
Net Income Per Diluted Common Share Attributable to Stepan Company		$ 0.03	$ (0.02)		$ 0.10	$ 0.06
Balance Sheet [Abstract]
Inventories		$ (28,363)			$ (28,363)			31,363
Other Non-Current Assets		1,415			1,415			(1,415)
Total Assets		(26,948)			(26,948)			29,948
Deferred Income Taxes		(5,551)			(5,551)			6,289
Retained Earnings		(21,397)			(21,397)			23,659
Total Liabilities and Equity		(26,948)			(26,948)			$ 29,948
Statement of Cash Flows [Abstract]
Net Income		$ 754	$ (414)		2,262	$ 1,344
Deferred Income Taxes					738	436
Changes in assets and liabilities:
Inventories					$ (3,000)	$ (1,780)
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[3]	The retained earnings and net income amounts for the noted line items have been changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO .
[4]	The 2019 amounts for the noted line items include an adjustment related to the Company’s first quarter 2019 adoption of ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

Change in Method of Accountin_5

Change in Method of Accounting for Inventory Valuation - Summary of Current Year Financial Statement Line Items If Company Does Not Changed Method of Accounting for U.S. Inventories from LIFO to FIFO (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018		Dec. 31, 2018
Income Statement [Abstract]
Cost of Sales	[1]	$ 374,180	$ 424,421		$ 1,158,785	$ 1,262,443
Gross Profit	[1]	77,402	83,576		254,970	264,755
Operating Income	[1],[2]	27,966	27,145		98,769	113,814
Income Before Provision for Income Taxes	[1],[2]	27,449	24,694		98,013	107,184
Provision for Income Taxes	[1]	1,569	2,940		16,945	20,033
Net Income	[1],[2]	25,880	21,754	[3]	81,068	87,151	[3]
Net Income Attributable to Stepan Company	[1],[2]	$ 25,889	$ 21,754		$ 81,091	$ 87,160
Net Income Per Diluted Common Share Attributable to Stepan Company	[1],[2]	$ 1.11	$ 0.93		$ 3.48	$ 3.74
Balance Sheet [Abstract]
Inventories	[2]	$ 203,303			$ 203,303			$ 231,528
Other Non-Current Assets	[2]	10,985			10,985			9,549
Total Assets	[2]	1,518,370			1,518,370			1,514,614
Deferred Income Taxes	[2]	25,218			25,218			24,961
Retained Earnings	[2],[4]	906,612			906,612			837,107
Total Liabilities and Equity	[2]	1,518,370			1,518,370			1,514,614
Statement of Cash Flows [Abstract]
Net Income	[1],[2]	25,880	$ 21,754	[3]	81,068	$ 87,151	[3]
Deferred Income Taxes	[2]				(2,291)	6,846
Changes in assets and liabilities:
Inventories	[2]				25,879	(23,366)
Effect of Change [Member]
Income Statement [Abstract]
Cost of Sales		(1,000)	549		(3,000)	(1,780)
Gross Profit		1,000	(549)		3,000	1,780
Operating Income		1,000	(549)		3,000	1,780
Income Before Provision for Income Taxes		1,000	(549)		3,000	1,780
Provision for Income Taxes		246	(135)		738	436
Net Income		754	(414)		2,262	1,344
Net Income Attributable to Stepan Company		$ 754	$ (414)		$ 2,262	$ 1,344
Net Income Per Diluted Common Share Attributable to Stepan Company		$ 0.03	$ (0.02)		$ 0.10	$ 0.06
Balance Sheet [Abstract]
Inventories		$ (28,363)			$ (28,363)			31,363
Other Non-Current Assets		1,415			1,415			(1,415)
Total Assets		(26,948)			(26,948)			29,948
Deferred Income Taxes		(5,551)			(5,551)			6,289
Retained Earnings		(21,397)			(21,397)			23,659
Total Liabilities and Equity		(26,948)			(26,948)			$ 29,948
Statement of Cash Flows [Abstract]
Net Income		754	$ (414)		2,262	$ 1,344
Deferred Income Taxes					738	436
Changes in assets and liabilities:
Inventories					(3,000)	$ (1,780)
As Computed under LIFO [Member]
Income Statement [Abstract]
Cost of Sales		373,180			1,155,785
Gross Profit		78,402			257,970
Operating Income		28,966			101,769
Income Before Provision for Income Taxes		28,449			101,013
Provision for Income Taxes		1,815			17,683
Net Income		26,634			83,330
Net Income Attributable to Stepan Company		$ 26,643			$ 83,353
Net Income Per Diluted Common Share Attributable to Stepan Company		$ 1.14			$ 3.58
Balance Sheet [Abstract]
Inventories		$ 174,940			$ 174,940
Other Non-Current Assets		12,400			12,400
Total Assets		1,491,422			1,491,422
Deferred Income Taxes		19,667			19,667
Retained Earnings		885,215			885,215
Total Liabilities and Equity		1,491,422			1,491,422
Statement of Cash Flows [Abstract]
Net Income		$ 26,634			83,330
Deferred Income Taxes					(1,553)
Changes in assets and liabilities:
Inventories					$ 22,879
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[3]	The retained earnings and net income amounts for the noted line items have been changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO .
[4]	The 2019 amounts for the noted line items include an adjustment related to the Company’s first quarter 2019 adoption of ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

Reconciliations of Equity - Rec

Reconciliations of Equity - Reconciliations of Total Equity (Detail) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
Reconciliations of total equity
Beginning Balance		$ 858,397		$ 789,096		$ 808,185	[1],[2]	$ 766,218	[2]
Issuance of common stock under stock option plan		667		214		2,830		3,488
Purchase of common stock		(7,003)		(1,500)		(13,184)		(13,500)
Stock-based and deferred compensation		1,408		2,311		2,657		3,618
Net income	[1],[3]	25,880		21,754	[2]	81,068		87,151	[2]
Other comprehensive income		(18,816)		(1,748)		(9,738)		(26,490)
Cash dividends paid:
Common stock		(5,626)		(5,065)		(16,911)		(15,225)
Other	[4]							(198)
Ending Balance		854,907	[1]	805,062		854,907	[1]	805,062
Common Stock [Member]
Reconciliations of total equity
Beginning Balance		26,453		26,279		26,309	[2]	26,071	[2]
Issuance of common stock under stock option plan		13		5		56		85
Stock-based and deferred compensation		15		3		116		131
Cash dividends paid:
Ending Balance		26,481		26,287		26,481		26,287
Additional Paid-in Capital [Member]
Reconciliations of total equity
Beginning Balance		188,781		177,779		182,881	[2]	170,408	[2]
Issuance of common stock under stock option plan		654		209		2,774		3,403
Stock-based and deferred compensation		1,969		2,380		5,749		6,557
Cash dividends paid:
Ending Balance		191,404		180,368		191,404		180,368
Treasury Stock [Member]
Reconciliations of total equity
Beginning Balance		(106,202)		(93,559)		(97,389)	[2]	(78,561)	[2]
Purchase of common stock		(7,003)		(1,500)		(13,184)		(13,500)
Stock-based and deferred compensation		(576)		(72)		(3,208)		(3,070)
Cash dividends paid:
Ending Balance		(113,781)		(95,131)		(113,781)		(95,131)
Accumulated Other Comprehensive Income (Loss) [Member]
Reconciliations of total equity
Beginning Balance		(137,723)		(124,290)		(141,483)	[2]	(99,563)	[2]
Other comprehensive income		(18,784)		(1,717)		(9,699)		(26,444)
Cash dividends paid:
Other	[5]					(5,325)
Ending Balance		(156,507)		(126,007)		(156,507)		(126,007)
Retained Earnings [Member]
Reconciliations of total equity
Beginning Balance		886,349		802,093		837,107	[2]	747,045	[2]
Net income		25,889		21,754	[2]	81,091		87,160	[2]
Cash dividends paid:
Common stock		(5,626)		(5,065)		(16,911)		(15,225)
Other						5,325	[5]	(198)	[4]
Ending Balance		906,612		818,782		906,612		818,782
Noncontrolling Interest [Member]
Reconciliations of total equity
Beginning Balance	[6]	739		794		760	[2]	818	[2]
Net income	[6]	(9)				(23)		(9)	[2]
Other comprehensive income	[6]	(32)		(31)		(39)		(46)
Cash dividends paid:
Ending Balance	[6]	$ 698		$ 763		$ 698		$ 763
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The retained earnings and net income amounts for the noted line items have been changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO .
[3]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[4]	Reflects 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
[5]	Reflects beginning retained earnings adjustment as a result of the Company’s first quarter 2019 adoption of ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income
[6]	Reflects the noncontrolling interest in the Company’s China joint venture.

Reconciliations of Equity - R_2

Reconciliations of Equity - Reconciliations of Total Equity (Parenthetical) (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Number of shares of common stock issued under stock option plan	13,256	5,032	56,385	85,394
Number of common stock shares purchased	73,821	16,833	144,457	156,524
Common stock	$ 0.25	$ 0.23	$ 0.75	$ 0.70
Common Stock [Member]
Number of shares of common stock issued under stock option plan	13,256	5,032	56,385	85,394
Additional Paid-in Capital [Member]
Number of shares of common stock issued under stock option plan	13,256	5,032	56,385	85,394
Treasury Stock [Member]
Number of common stock shares purchased	73,821	16,833	144,457	156,524
Retained Earnings [Member]
Common stock	$ 0.25	$ 0.23	$ 0.75	$ 0.70

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Unamortized debt issuance cost	$ 789,000	$ 978,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values and Related Carrying Values of Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value	$ 232,709	$ 277,058
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value	$ 237,766	$ 274,119

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	$ 26,389	$ 25,082
Derivative assets:
Foreign currency contracts	91	185
Total assets at fair value	26,480	25,267
Derivative liabilities:
Foreign currency contracts	280	10
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	26,389	25,082
Derivative assets:
Total assets at fair value	26,389	25,082
Level 2 [Member]
Derivative assets:
Foreign currency contracts	91	185
Total assets at fair value	91	185
Derivative liabilities:
Foreign currency contracts	$ 280	$ 10

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	$ 35,857,965	$ 28,870,081
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)	9 Months Ended
	Sep. 30, 2019
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	1 year 10 months 24 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 9 months 18 days
SARs [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

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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Compensation expense	$ 2,273	$ 3,335	$ 7,045	$ 6,722

Stock-based Compensation - Unre

Stock-based Compensation - Unrecognized Compensation Costs for Stock Options, Stock Awards and SARs (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs for stock options, stock awards and SARs	$ 2,270	$ 1,655
Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs for stock options, stock awards and SARs	4,114	3,180
SARs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs for stock options, stock awards and SARs	$ 4,964	$ 3,566

Stock-based Compensation - Shar

Stock-based Compensation - Share Based Payment Awards Granted in Period (Detail)	9 Months Ended
	Sep. 30, 2019shares
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted in period	72,965
Stock Awards (at target) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards granted in period	45,327
SARs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards granted in period	162,624

Inventories - Composition of In

Inventories - Composition of Inventories (Detail) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Finished goods		$ 148,320	$ 163,617
Raw materials		54,983	67,911
Total inventories	[1]	$ 203,303	$ 231,528
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)Country
Operating Leased Assets [Line Items]
Right of use asset	$ 38,027
Operating lease, liability	$ 38,037
Number of countries leases reside | Country	4
Percentage of value of leases reside	94.00%
Minimum [Member]
Operating Leased Assets [Line Items]
Lessee, operating lease, term of contract	1 year
Maximum [Member]
Operating Leased Assets [Line Items]
Lessee, operating lease, term of contract	10 years
Railcars [Member]
Operating Leased Assets [Line Items]
Percentage of lease asset categories	50.00%
Real Estate [Member]
Operating Leased Assets [Line Items]
Percentage of lease asset categories	37.00%
Real Estate [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lessee, operating lease, term of contract	1 year
Real Estate [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lessee, operating lease, term of contract	50 years
Real Estate and Railcars [Member]
Operating Leased Assets [Line Items]
Operating lease, liability	$ 1,900
Real Estate and Railcars [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Lessee, operating lease, term of contract	1 year
Real Estate and Railcars [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Lessee, operating lease, term of contract	5 years
ASC 842 [Member]
Operating Leased Assets [Line Items]
Right of use asset	$ 42,400
Operating lease, liability	$ 42,400

Leases - Schedule of Lease Cost

Leases - Schedule of Lease Cost and Other Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lease Cost
Operating lease cost	$ 2,698	$ 8,097
Short-term lease cost	1,249	3,367
Variable lease cost	303	884
Total lease cost	4,250	12,348
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flow from operating leases	2,718	8,139
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 1,593	$ 2,482

Leases - Schedule of Lease Liab

Leases - Schedule of Lease Liability Payments (Detail) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
2019 (excluding the nine months ended September 30, 2019)	$ 2,734
2020	9,771
2021	6,899
2022	5,699
2023	4,457
Subsequent to 2023	18,376
Total Undiscounted Cash Flows	47,936
Less: Imputed interest	(9,899)
Present value	38,037
Current operating lease liabilities	8,973	[1]
Non-current operating lease liabilities	29,064
Total lease liabilities	$ 38,037
[1]	This item is included in Accrued liabilities line on the Company’s Condensed Consolidated Balance Sheet

Leases - Schedule of Operating

Leases - Schedule of Operating Leases Weighted Average, Remaining Lease Term and Discount Rate (Detail)	Sep. 30, 2019
Leases [Abstract]
Weighted-average remaining lease term-operating leases	9 years
Weighted-average discount rate-operating leases	4.30%

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments Under ASC 840 (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 9,740
2020	8,294
2021	6,027
2022	5,242
2023	4,101
Subsequent to 2023	16,593
Total minimum future rental payments	$ 49,997

Contingencies - Additional Info

Contingencies - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Site Contingency [Line Items]
Environmental losses accrual	$ 23,900,000		$ 23,400,000
Cash expenitures related to legal and environmental matters	$ 2,800,000	$ 1,000,000
Contribution for future response costs	5.00%
Wilmington Site [Member]
Site Contingency [Line Items]
Payment of environmental response costs	$ 2,800,000
Minimum [Member]
Site Contingency [Line Items]
Environmental and legal losses	23,900,000
Maximum [Member]
Site Contingency [Line Items]
Environmental and legal losses	$ 45,600,000

Postretirement Benefit Plans -

Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ (159)	$ 208	$ (247)	$ 466
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,640	1,566	4,962	4,645
Expected return on plan assets	(2,365)	(2,320)	(7,087)	(6,962)
Amortization of net actuarial loss	563	987	1,867	2,860
Net periodic benefit cost	(162)	233	(258)	543
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	134	138	416	430
Expected return on plan assets	(190)	(216)	(589)	(673)
Amortization of net actuarial loss	59	53	184	166
Net periodic benefit cost	$ 3	$ (25)	$ 11	$ (77)

Postretirement Benefit Plans _2

Postretirement Benefit Plans - Defined Benefit Pension Plans - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019USD ($)
Defined Contribution Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Balance of trust assets	$ 1,670,000
United States [Member] | Unfunded Plan [Member] | Non-qualified Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions or payments to defined benefit plans	312,000
Employer contributions or payments	256,000
U.K Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions or payments to defined benefit plans	476,000
Employer contributions or payments	$ 408,000

Postretirement Benefit Plans _3

Postretirement Benefit Plans - Defined Contribution Plan Expenses for Company's Qualified Contribution Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution plan expenses	$ 2,344	$ 2,497	$ 7,814	$ 7,970
Retirement Savings Contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution plan expenses	1,777	1,738	5,401	5,201
Profit Sharing Contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Total defined contribution plan expenses	$ 567	$ 759	$ 2,413	$ 2,769

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		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Computation of Basic Earnings per Share
Net income attributable to Stepan Company	[1],[2]	$ 25,889	$ 21,754	$ 81,091	$ 87,160
Weighted-average number of common shares outstanding		23,025	22,986	23,070	23,036
Basic earnings per share	[1],[2]	$ 1.12	$ 0.95	$ 3.52	$ 3.78
Computation of Diluted Earnings per Share
Net income attributable to Stepan Company	[1]	$ 25,889	$ 21,754	$ 81,091	$ 87,160
Weighted-average number of common shares outstanding		23,025	22,986	23,070	23,036
Add weighted-average net shares related to unvested stock awards (under treasury stock method)		1	3	2	2
Weighted-average shares applicable to diluted earnings		23,300	23,288	23,320	23,324
Net Income Per Diluted Common Share Attributable to Stepan Company	[1],[2]	$ 1.11	$ 0.93	$ 3.48	$ 3.74
Stock Option [Member]
Computation of Diluted Earnings per Share
Add weighted-average net shares from assumed exercise of options (under treasury stock method)	[3]	102	103	95	103
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)	[3]	135	113	120	111
Performance Stock Award [Member]
Computation of Diluted Earnings per Share
Add weighted-average net shares from assumed exercise of options (under treasury stock method)		37	83	33	72
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[3]	Options/SARs to acquire

Earnings Per Share - Computat_2

Earnings Per Share - Computations of Basic and Diluted Earnings Per Share (Parenthetical) (Detail) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Options and Stock Appreciation Rights (SARs) [Member]
Earnings Per Share Basic [Line Items]
Options/SARs to purchase shares of common stock were excluded from the computations of diluted earnings per share	142,833	65,919

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Additional Information (Detail) $ in Thousands	Jan. 01, 2019USD ($)
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from Tax Act	$ 5,325

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	[1]			$ 807,425
Other comprehensive income before reclassifications		$ (19,255)	$ (2,503)	(11,251)	$ (28,730)
Amounts reclassified from AOCI		471	786	1,552	2,286
Remeasurement adjustment related to the Tax Act	[2]			(5,325)
Net current-period other comprehensive income		(18,784)	(1,717)	(15,024)	(26,444)
Ending Balance	[1]	854,209		854,209
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(100,477)	(96,788)	(108,481)	(70,561)
Other comprehensive income before reclassifications		(19,255)	(2,503)	(11,251)	(28,730)
Net current-period other comprehensive income		(19,255)	(2,503)	(11,251)	(28,730)
Ending Balance		(119,732)	(99,291)	(119,732)	(99,291)
Defined Benefit Pension Plan Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(37,323)	(27,588)	(33,083)	(29,093)
Amounts reclassified from AOCI		473	788	1,558	2,293
Remeasurement adjustment related to the Tax Act	[2]			(5,325)
Net current-period other comprehensive income		473	788	(3,767)	2,293
Ending Balance		(36,850)	(26,800)	(36,850)	(26,800)
Cash Flow Hedge Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		77	86	81	91
Amounts reclassified from AOCI		(2)	(2)	(6)	(7)
Net current-period other comprehensive income		(2)	(2)	(6)	(7)
Ending Balance		75	84	75	84
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(137,723)	(124,290)	(141,483)	(99,563)
Net current-period other comprehensive income		(18,784)
Ending Balance		$ (156,507)	$ (126,007)	$ (156,507)	$ (126,007)
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	Represents reclassification of the stranded tax effects resulting from the U.S. Tax Cuts and Jobs Act (Tax Act) from accumulated other comprehensive income (loss) to retained earnings in accordance with ASU 2018-02. See Note 19 for more details.

Accumulated Other Comprehensi_5

Accumulated Other Comprehensive Income (Loss) - Summary of Amounts Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income Before Provision for Income Taxes	[1],[2]	$ 27,449	$ 24,694	$ 98,013	$ 107,184
Tax benefit	[2]	(1,569)	(2,940)	(16,945)	(20,033)
Cost of Sales	[2]	374,180	424,421	1,158,785	1,262,443
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]	(622)	(1,040)	(2,051)	(3,026)
Tax benefit	[3]	149	252	493	733
Income applicable to common stock	[3]	(473)	(788)	(1,558)	(2,293)
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	2	6	7
Income applicable to common stock	[3]	2	2	6	7
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	2	6	7
Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income applicable to common stock	[3]	$ (471)	$ (786)	$ (1,552)	$ (2,286)
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[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 10 for additional details).

Segment Reporting - Additional

Segment Reporting - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Reporting - Operating S

Segment Reporting - Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net sales	$ 451,582	$ 507,997	$ 1,413,755	$ 1,527,198
Surfactants [Member]
Segment Reporting Information [Line Items]
Net sales	299,719	346,884	962,749	1,062,708
Polymers [Member]
Segment Reporting Information [Line Items]
Net sales	135,089	141,646	395,904	404,446
Specialty Products [Member]
Segment Reporting Information [Line Items]
Net sales	$ 16,774	$ 19,467	$ 55,102	$ 60,044

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation of Segment Information to Income Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Operating Income	[1],[2]	$ 27,966	$ 27,145	$ 98,769	$ 113,814
Business restructuring expenses (Note 17)		(459)	(1,715)	(1,642)	(2,346)
Interest expense, net		(1,402)	(2,797)	(5,021)	(8,620)
Other, net		885	346	4,265	1,990
Income Before Provision for Income Taxes	[1],[2]	27,449	24,694	98,013	107,184
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Income	[1]	45,204	50,736	158,435	167,776
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating Income	[1]	19,660	28,824	88,913	104,370
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating Income	[1]	23,283	19,259	58,148	56,863
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating Income		2,261	2,653	11,374	6,543
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[3]	$ (16,779)	$ (21,876)	$ (58,024)	$ (51,616)
[1]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from LIFO to FIFO.
[2]	The 2018 amounts for the noted line items have been retrospectively changed from the amounts originally reported as a result of the Company’s first quarter 2019 change in method of accounting for U.S. inventory valuation from the last in, first out (LIFO) basis to the first in, first out (FIFO) basis.
[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 C_3

Revenue from Contracts with Customers - Additional Information (Detail)	Sep. 30, 2019USD ($)
Revenue From Contract With Customer [Abstract]
Contract assets	$ 0
Contract liabilities	$ 0

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Summary of Geographic Disaggregation of Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Net sales	$ 451,582	$ 507,997	$ 1,413,755	$ 1,527,198
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	277,231	309,629	873,097	941,991
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	99,781	116,490	318,045	354,827
Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	52,732	59,538	159,148	159,265
Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	21,838	22,340	63,465	71,115
Surfactants [Member]
Disaggregation Of Revenue [Line Items]
Net sales	299,719	346,884	962,749	1,062,708
Surfactants [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	178,799	205,032	584,816	643,466
Surfactants [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	57,190	68,120	183,028	212,556
Surfactants [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	51,940	58,560	156,709	156,827
Surfactants [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	11,790	15,172	38,196	49,859
Polymers [Member]
Disaggregation Of Revenue [Line Items]
Net sales	135,089	141,646	395,904	404,446
Polymers [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	84,397	87,720	242,154	248,160
Polymers [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	39,852	45,780	126,042	132,592
Polymers [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	792	978	2,439	2,438
Polymers [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	10,048	7,168	25,269	21,256
Specialty Products [Member]
Disaggregation Of Revenue [Line Items]
Net sales	16,774	19,467	55,102	60,044
Specialty Products [Member] | North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	14,035	16,877	46,127	50,365
Specialty Products [Member] | Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	2,739	2,590	8,975	9,679
Specialty Products [Member] | Latin America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	0	0	0	0
Specialty Products [Member] | Asia [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0

Debt - Debt (Detail)

Debt - Debt (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total debt	$ 231,920	$ 276,080
Less current maturities	24,137	37,058
Long-term debt	207,783	239,022
Unsecured private placement 3.95% note [Member]
Debt Instrument [Line Items]
Total debt	$ 99,673	$ 99,640
Debt instrument interest rate percentage	3.95%	3.95%
Unsecured private placement 3.95% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2021	2021
Unsecured private placement 3.95% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2027	2027
Unsecured private placement 3.86% note [Member]
Debt Instrument [Line Items]
Total debt	$ 85,409	$ 99,653
Debt instrument interest rate percentage	3.86%	3.86%
Unsecured private placement 3.86% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2019	2019
Unsecured private placement 3.86% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2025	2025
Unsecured private placement 4.86% note [Member]
Debt Instrument [Line Items]
Total debt	$ 46,271	$ 46,243
Debt instrument interest rate percentage	4.86%	4.86%
Unsecured private placement 4.86% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2019	2019
Unsecured private placement 4.86% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2023	2023
Unsecured private placement 5.88% note [Member]
Debt Instrument [Line Items]
Total debt		$ 22,772
Debt instrument interest rate percentage	5.88%	5.88%
Unsecured private placement 5.88% note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Maturity Dates	2019	2019
Unsecured private placement 5.88% note [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maturity Dates	2022	2022
Debt of foreign subsidiaries Unsecured bank debt, foreign currency [Member]
Debt Instrument [Line Items]
Total debt	$ 567	$ 7,772
Maturity Dates	2019	2019

Debt - Debt (Parenthetical) (De

Debt - Debt (Parenthetical) (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Unamortized debt issuance cost	$ 789,000	$ 978,000
Unsecured private placement 3.95% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	327,000	360,000
Unsecured private placement 3.86% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	305,000	347,000
Unsecured private placement 4.86% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	157,000	186,000
Unsecured private placement 5.88% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	$ 0	$ 85,000

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	Jun. 12, 2019	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Unamortized debt issuance cost		$ 789,000	$ 978,000
Multi currency revolving credit agreement [Member]
Debt Instrument [Line Items]
Revolving credit agreement		$ 350,000,000
Credit agreement secured date		Jan. 30, 2023
Letters of Credit Outstanding		$ 5,009,000
Debt Outstanding		0
Unused Revolving credit		344,991,000
Unrestricted retained earnings		$ 267,903,000	$ 214,101,000
Series 2010-A Senior Notes due June 1, 2022 [Member]
Debt Instrument [Line Items]
Credit agreement secured date		Jun. 1, 2022
Prepaid outstanding principal	$ 17,100,000
Debt instrument interest rate percentage	5.88%
Make-whole amount	$ 1,173,000
Unamortized debt issuance cost	$ 74,000

Other, Net - Other Net in Conso

Other, Net - Other Net in Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Nonoperating Income Expense [Abstract]
Foreign exchange gain (loss)	$ 374	$ (274)	$ 333	$ 895
Investment income	106	91	309	320
Realized and unrealized gain (loss) on investments	(324)	737	2,806	1,241
Net periodic pension benefit cost	159	(208)	247	(466)
Gain on sale of asset	570		570
Other, net	$ 885	$ 346	$ 4,265	$ 1,990

Business Restructuring - Additi

Business Restructuring - Additional Information (Detail)	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2019USD ($)Employees	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Restructuring Cost And Reserve [Line Items]
Business restructuring	$ 459,000		$ 1,715,000		$ 1,642,000	$ 2,346,000
Netherlands [Member]
Restructuring Cost And Reserve [Line Items]
Number positions eliminated | Employees					5
Severance costs					$ 396,000
Germany [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs					$ 1,968,000
Germany [Member] | Surfactants [Member] | Asset and Spare Part [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs							$ 1,404,000
Fieldsboro, NJ [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring		$ 251,000		$ 915,000
Longford Mills [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Number positions eliminated | Employees					30
Business restructuring					$ 6,885,000
Decommissioning expense	$ 290,000
Early Termination of Lease Expenses [Member] | Netherlands [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring					122,000
Termination Benefits [Member] | Longford Mills [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring					1,644,000
Decommissioning Costs [Member] | Germany [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring costs					564,000
Other Expense [Member] | Longford Mills [Member] | Surfactants [Member]
Restructuring Cost And Reserve [Line Items]
Business restructuring					$ 5,241,000

Acquisition - Additional Inform

Acquisition - Additional Information (Detail)	Mar. 26, 2018USD ($)ft²T	Sep. 30, 2018USD ($)
Business Acquisition [Line Items]
Paid from cash on hand		$ 21,475,000
2018 Acquisition [Member] | 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	$ 22,852,000
Intangible assets identified related to acquisition	$ 0

Acquisition - Summary of Assets

Acquisition - Summary of Assets Acquired (Detail) - 2018 Acquisition [Member] - BASF Mexicana, S.A. DE C.V. [Member] $ in Thousands	Mar. 26, 2018USD ($)
Assets:
Property, plant and equipment	$ 14,464
Inventory	5,687
Value-added tax receivables	2,701
Total assets acquired	$ 22,852

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements - Additional Information (Detail) $ in Thousands	Jan. 01, 2019USD ($)
Accounting Changes And Error Corrections [Abstract]
Reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from Tax Act	$ 5,325