Earnings Per Share ("EPS") - Calculation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss) Attributable to Kraton, Basic:
As reported	$ (4,033)	$ 15,560	$ 27,941	$ 111,048
Amounts allocated to unvested restricted shares	(77)	329	541	2,422
Amounts available to common stockholders	(3,956)	15,231	27,400	108,626
Net Income (Loss) Attributable to Kraton, Diluted:
Amounts allocated to unvested restricted shares	77	(329)	(541)	(2,422)
Amounts reallocated to unvested restricted shares	77	(323)	(533)	(2,390)
Amounts available to stockholders and assumed conversions	$ (3,956)	$ 15,237	$ 27,408	$ 108,658
Weighted Average Shares Outstanding, Basic:
As reported	31,223	30,874	31,151	30,809
Amounts allocated to unvested restricted shares	(598)	(653)	(603)	(672)
Amounts available to common stockholders	30,625	30,221	30,548	30,137
Weighted Average Shares Outstanding, Diluted:
Amounts allocated to unvested restricted shares	(598)	(653)	(603)	(672)
Non participating share units	0	205	175	208
Stock options added under the treasury stock method	0	357	283	212
Amounts available to stockholders and assumed conversions	30,625	30,783	31,006	30,557
Earnings (loss) per share, basic (in dollars per share)	$ (0.13)	$ 0.50	$ 0.90	$ 3.60
Earnings (loss) per share, diluted (in dollars per share)	$ (0.13)	$ 0.49	$ 0.88	$ 3.56