Summary of Significant Accounting Policies - Additional Information (Detail) MMBTU in Millions		12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2019 USD ($) MMBTU Customer Subsidiary	Dec. 31, 2018 USD ($) Customer	Dec. 31, 2017 USD ($) Customer
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents		$ 315,383,000	$ 300,194,000
Single customer comprised more than 10 percent of the Company's consolidated net sales | Customer		0	0	0
Cost of maintenance and repairs		$ 58,464,000	$ 57,010,000	$ 51,926,000
Total research and development expenses		$ 34,139,000	$ 33,519,000	$ 33,169,000
Capitalized Environmental expenditures depreciation period		10 years
Indefinite-life intangible assets		$ 0
Number of foreign subsidiaries | Subsidiary		3
Reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from Tax Act	$ 5,325,000
Natural Gas [Member]
Summary Of Significant Accounting Policy [Line Items]
Volume in derivative contract | MMBTU		0.9
Purchased Contract Price		$ 2,442,000
Non-compete Agreements [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		5 years
Trademarks [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		11 years
Supply contracts [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		4 years
Building [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		30 years
Building Improvements [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		15 years
Minimum [Member]
Summary Of Significant Accounting Policy [Line Items]
Percentage of Tax benefit recognized		50.00%
Minimum [Member] | Patents [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		10 years
Minimum [Member] | Customer Relationships [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		10 years
Minimum [Member] | Know-how [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		8 years
Minimum [Member] | Manufacturing Equipment [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		10 years
Minimum [Member] | Furniture and Fixtures [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		5 years
Minimum [Member] | Vehicles [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		3 years
Minimum [Member] | Computers Equipment And Software [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		3 years
Maximum [Member] | Patents [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		15 years
Maximum [Member] | Customer Relationships [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		25 years
Maximum [Member] | Know-how [Member]
Summary Of Significant Accounting Policy [Line Items]
Finite-lived intangible asset, useful life		14 years
Maximum [Member] | Manufacturing Equipment [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		15 years
Maximum [Member] | Furniture and Fixtures [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		10 years
Maximum [Member] | Vehicles [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		5 years
Maximum [Member] | Computers Equipment And Software [Member]
Summary Of Significant Accounting Policy [Line Items]
Lives used for calculating depreciation expense		10 years
Money Market Funds [Member]
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents		$ 110,700,000
Demand Deposits and Certificates of Deposit [Member]
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents		105,700,000
Non-U.S. Subsidiaries [Member]
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents		$ 99,000,000.0
Nanjing Stepan Jinling Chemical Limited Liability Company [Member]
Summary Of Significant Accounting Policy [Line Items]
Ownership percentage		80.00%