Reporting For Segments (Net Sales To External Customers By Segment) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net sales	$ 259,950	$ 241,877	$ 204,801	$ 252,326	$ 244,778	$ 245,339	$ 260,958	$ 263,382	$ 958,954	$ 1,014,457	$ 1,074,696
Functional Coatings [Member]
Segment Reporting Information [Line Items]
Net sales									608,192	644,783	683,669
Color Solutions [Member]
Segment Reporting Information [Line Items]
Net sales									$ 350,762	$ 369,674	$ 391,027