Ecovyst, Inc. Annual report pursuant to Section 13 and 15(d)

Earnings per Share - Anti-dilutive Shares (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Performance based restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	1,769,447	1,731,522	0
Performance based stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	586,523	417,086	293,150
Restricted stock awards and restricted units
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	0	751,410	0
Stock option
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	621,747	1,381,352	1,085,152