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

Accumulated Other Comprehensive Income - Pre-tax and After-tax Components of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
After-tax amount
Pre-tax amount	$ 3,816	$ 20,824	$ (10,559)	$ 63,568
Tax benefit/(expense)	1,688	(2,295)	(666)	(6,625)
Total other comprehensive income (loss)	5,504	18,529	(11,225)	56,943
Defined benefit and other postretirement plans:
After-tax amount
Pre-tax amount	(69)	(33)	1,740	(261)
Tax benefit/(expense)	17	13	(435)	38
Total other comprehensive income (loss)	(52)	(20)	1,305	(223)
Net gain (loss) from hedging activities
After-tax amount
Pre-tax amount	494	(486)	4,143	(5,373)
Tax benefit/(expense)	(124)	185	(1,037)	2,047
Total other comprehensive income (loss)	370	(301)	3,106	(3,326)
Foreign currency translation
After-tax amount
Pre-tax amount	3,391	21,343	(16,442)	69,202
Tax benefit/(expense)	1,795	(2,493)	806	(8,710)
Total other comprehensive income (loss)	$ 5,186	$ 18,850	$ (15,636)	$ 60,492