Goodwill and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	$ 47,638		$ 47,638		$ 42,215
Definite-lived, Accumulated Amortization	(32,649)		(32,649)		(28,380)
Definite-lived, Net Carrying Amount	14,989		14,989		13,835
Total other intangible assets, Gross Carrying Amount	56,708		56,708		51,285
Total other intangible assets, Accumulated Amortization	(32,649)		(32,649)		(28,380)
Accumulated Impairment	(4,953)		(4,953)		(4,953)
Total other intangible assets, Net Carrying Amount	19,106		19,106		17,952
Amortization expense	1,600	$ 1,600	4,600	$ 3,900
Trade name
GOODWILL AND OTHER INTANGIBLE ASSETS
Indefinite lived, Gross Carrying Amount	9,070		9,070		9,070
Indefinite lived, Accumulated Impairment	(4,953)		(4,953)		(4,953)
Indefinite lived, Net Carrying Amount	4,117		4,117		4,117
Customer lists
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	38,372		38,372		32,772
Definite-lived, Accumulated Amortization	(26,844)		(26,844)		(22,726)
Definite-lived, Net Carrying Amount	11,528		11,528		10,046
Trade name
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	255		255		255
Definite-lived, Accumulated Amortization	(170)		(170)		(151)
Definite-lived, Net Carrying Amount	85		85		104
Patents and other intangibles
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	9,011		9,011		9,188
Definite-lived, Accumulated Amortization	(5,635)		(5,635)		(5,503)
Definite-lived, Net Carrying Amount	$ 3,376		$ 3,376		$ 3,685