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, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
After-tax amount
Pre-tax amount	$ (10,047)			$ 3,816			$ 998	$ (10,559)
Tax benefit/(expense)	(3,849)			1,688			(4,422)	(666)
Total other comprehensive income (loss)	(13,896)	$ 4,887	$ 5,585	5,504	$ (27,565)	$ 10,836	(3,424)	(11,225)
Amortization of net gains and (losses)
After-tax amount
Pre-tax amount	(10)			(50)			(26)	1,798
Tax benefit/(expense)	4			13			8	(449)
Total other comprehensive income (loss)	(6)			(37)			(18)	1,349
Amortization of prior service cost
After-tax amount
Pre-tax amount	(63)			(19)			(128)	(58)
Tax benefit/(expense)	10			4			26	14
Total other comprehensive income (loss)	(53)			(15)			(102)	(44)
Benefit plans, net
After-tax amount
Pre-tax amount	(73)			(69)			(154)	1,740
Tax benefit/(expense)	14			17			34	(435)
Total other comprehensive income (loss)	(59)			(52)			(120)	1,305
Net (loss) gain from hedging activities
After-tax amount
Pre-tax amount	46			494			(3,579)	4,143
Tax benefit/(expense)	(11)			(124)			895	(1,037)
Total other comprehensive income (loss)	35			370			(2,684)	3,106
Foreign currency translation
After-tax amount
Pre-tax amount	(10,020)			3,391			4,731	(16,442)
Tax benefit/(expense)	(3,852)			1,795			(5,351)	806
Total other comprehensive income (loss)	$ (13,872)			$ 5,186			$ (620)	$ (15,636)