Condensed Consolidated Statements of Income - USD ($)
shares in Thousands, $ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Income Statement [Abstract]        
Net Sales $ 487,814 $ 445,030 $ 1,451,184 $ 1,345,530
Cost of Sales 412,212 361,635 1,193,518 1,075,705
Gross Profit 75,602 83,395 257,666 269,825
Operating Expenses:        
Selling 13,740 13,990 40,484 42,252
Administrative 18,557 18,958 54,376 55,350
Research, development and technical services 12,699 14,268 40,416 42,306
Deferred compensation expense (129) 7,441 5,263 12,595
Total Operating expenses 44,867 54,657 140,539 152,503
Business restructuring expenses (Note 14) 426   1,798 1,061
Operating Income 30,309 28,738 115,329 116,261
Other Income (Expense):        
Interest, net (2,763) (2,824) (8,618) (9,855)
Other, net (Note 13) 1,766 1,229 3,994 401
Nonoperating Income (Expense), Total (997) (1,595) (4,624) (9,454)
Income Before Provision for Income Taxes 29,312 27,143 110,705 106,807
Provision for Income Taxes [1] 7,459 5,776 29,044 29,020
Net Income [1] 21,853 21,367 81,661 77,787
Net (Income) Loss Attributable to Noncontrolling Interests (Note 2) 46 (5) 33 (13)
Net Income Attributable to Stepan Company [1] $ 21,899 $ 21,362 $ 81,694 $ 77,774
Net Income Per Common Share Attributable to Stepan Company (Note 9):        
Basic [1] $ 0.95 $ 0.94 $ 3.56 $ 3.42
Diluted [1] $ 0.94 $ 0.92 $ 3.50 $ 3.38
Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 9):        
Basic 22,971 22,819 22,941 22,771
Diluted [1] 23,374 23,148 23,361 23,017
Dividends Declared Per Common Share $ 0.21 $ 0.19 $ 0.62 $ 0.57
[1] The 2016 amounts for the noted items have been immaterially changed from the amounts originally reported as a result of the Company’s fourth quarter 2016 adoption of Accounting Standards Update (ASU) No. 2016-9, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.