Summary of Significant Accounting Policies - Additional Information (Detail) MMBTU in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) MMBTU Customer Subsidiary	Dec. 31, 2014 USD ($) Customer	Dec. 31, 2013 USD ($) Customer	Dec. 31, 2012 USD ($)
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents	$ 176,143,000	$ 85,215,000	$ 133,347,000	$ 76,875,000
Single customer comprised more than 10 percent of the Company's consolidated net sales | Customer	0	0	0
Bad debt allowance	$ 1,106,000	$ 4,625,000	$ 719,000
Percentage of LIFO Inventory	72.00%	67.00%
Cost of maintenance and repairs	$ 52,549,000	$ 55,923,000	48,683,000
Total research and development expenses	$ 30,315,000	27,236,000	$ 28,782,000
Capitalized Environmental expenditures depreciation period	10 years
Indefinite-life intangible assets	$ 0
Number of foreign subsidiaries | Subsidiary	1
Natural Gas [Member]
Summary Of Significant Accounting Policy [Line Items]
Volume in derivative contract | MMBTU	1.1
Purchased Contract Price	$ 3,561,000
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] | Machinery and 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] | Machinery and 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
Polymers [Member]
Summary Of Significant Accounting Policy [Line Items]
Bad debt allowance		$ 2,388,000
Money Market Funds [Member]
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents	$ 68,800,000
Demand Deposits [Member]
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents	20,200,000
Non U S Subsidiaries [Member]
Summary Of Significant Accounting Policy [Line Items]
Cash and cash equivalents	$ 87,100,000
Stepan China [Member]
Summary Of Significant Accounting Policy [Line Items]
Ownership percentage	80.00%