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

Financial Instruments - Effect on Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amount of gain (loss) recognized in OCI on derivatives
Amount of gain (loss) recognized in OCI on derivatives	$ (4,514)	$ (344)	$ (6,060)
Amount of gain (loss) reclassified from AOCI into income
Amount of gain (loss) reclassified from AOCI into income	(960)	97	(262)
Interest rate caps
Amount of gain (loss) recognized in OCI on derivatives
Amount of gain (loss) recognized in OCI on derivatives	(3,304)	(981)	(4,760)
Interest rate caps \| Interest expense
Amount of gain (loss) reclassified from AOCI into income
Amount of gain (loss) reclassified from AOCI into income	(625)	(256)	(40)
Natural gas swaps
Amount of gain (loss) recognized in OCI on derivatives
Amount of gain (loss) recognized in OCI on derivatives	(1,210)	637	(1,300)
Natural gas swaps \| Cost of goods sold
Amount of gain (loss) reclassified from AOCI into income
Amount of gain (loss) reclassified from AOCI into income	$ (335)	$ 353	$ (222)