Ecovyst, Inc. Quarterly report pursuant to Section 13 or 15(d)

Income Taxes (Details)	3 Months Ended		9 Months Ended
Income Taxes (Details)	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate	239.90%	26.90%	(304.20%)	(67.10%)