BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Warranty, Accrued Liabilities, and Basic and Diluted Income per Share (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Changes in the reserve for product warranty claims
Warranty reserve at beginning of the year	$ 971	$ 922	$ 830
Warranty reserves acquired		117
Provision	210	(13)	234
Warranty expenditures	(101)	(34)	(200)
Effect of foreign currency translation	(5)	(21)	58
Warranty reserve at end of year	1,075	971	922
ACCRUED LIABILITIES
Compensation and fringe benefits				$ 12,967	$ 11,642
Warranty reserve	$ 1,075	$ 971	$ 922	1,075	971
Income taxes payable				2,231	1,182
Right of use liability				3,203
Other accrued expenses				3,525	4,927
Accrued liabilities				$ 23,001	$ 18,722
Basic and Diluted Income per Share
Basic weighted average shares outstanding	9,398	9,265	9,153
Dilutive effect of equity awards	63	105	122
Diluted weighted average shares outstanding	9,461	9,370	9,275
Minimum
Warranty
Warranty period	3 months
Maximum
Warranty
Warranty period	2 years