Goodwill and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	$ 47,738		$ 47,738		$ 42,215
Definite-lived, Accumulated Amortization	(31,014)		(31,014)		(28,380)
Definite-lived, Net Carrying Amount	16,724		16,724		13,835
Total other intangible assets, Gross Carrying Amount	56,808		56,808		51,285
Total other intangible assets, Accumulated Amortization	(31,014)		(31,014)		(28,380)
Total other intangible assets, Accumulated Impairment	(4,953)		(4,953)		(4,953)
Total other intangible assets, Net Carrying Amount	20,841		20,841		17,952
Amortization expense	1,600	$ 1,100	3,000	$ 2,200
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	38,472		38,472		32,772
Definite-lived, Accumulated Amortization	(25,389)		(25,389)		(22,726)
Definite-lived, Net Carrying Amount	13,083		13,083		10,046
Trade name
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	255		255		255
Definite-lived, Accumulated Amortization	(164)		(164)		(151)
Definite-lived, Net Carrying Amount	91		91		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	(5,461)		(5,461)		(5,503)
Definite-lived, Net Carrying Amount	$ 3,550		$ 3,550		$ 3,685