Goodwill and Other Intangible Assets - Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	$ 41,018		$ 41,018		$ 35,682
Definite-lived, Accumulated Amortization	(27,150)		(27,150)		(24,321)
Definite-lived, Net Carrying Amount	13,868		13,868		11,361
Total other intangible assets, Gross Carrying Amount	50,088		50,088		44,752
Total other intangible assets, Accumulated Impairment	(4,953)		(4,953)		(4,953)
Total other intangible assets, Net Carrying Amount	17,985		17,985		15,478
Amortization expense	1,600	$ 1,500	3,900	$ 5,300
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	31,525		31,525		26,036
Definite-lived, Accumulated Amortization	(21,622)		(21,622)		(19,051)
Definite-lived, Net Carrying Amount	9,903		9,903		6,985
Trade name
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	255		255		255
Definite-lived, Accumulated Amortization	(145)		(145)		(125)
Definite-lived, Net Carrying Amount	110		110		130
Patents and other intangibles
GOODWILL AND OTHER INTANGIBLE ASSETS
Definite-lived, Gross Carrying Amount	9,238		9,238		9,391
Definite-lived, Accumulated Amortization	(5,383)		(5,383)		(5,145)
Definite-lived, Net Carrying Amount	$ 3,855		$ 3,855		$ 4,246