Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 84,939	$ 72,289
Accounts receivable, net of allowance for doubtful accounts of $1,036 and $1,171, at December 31, 2020 and 2019, respectively	71,372	76,092
Inventories	100,133	107,276
Unbilled receivables	14,135	16,318
Other current assets	9,637	11,206
Total current assets	280,216	283,181
Property, plant and equipment, net	34,501	41,943
Right-of-use assets	14,217	18,504
Intangible assets, net	65,789	72,364
Goodwill	23,966	21,993
Deferred income taxes	5,705	3,731
Other assets	29,472	27,201
Total assets	453,866	468,917
Current liabilities:
Accounts payable	39,774	44,169
Accrued expenses	28,476	26,918
Current maturities of long-term debt	5,286	5,489
Operating lease liability, current	6,591	7,377
Other current liabilities	7,409	6,265
Total current liabilities	87,536	90,218
Long-term liabilities:
Long-term debt	110,294	138,215
Operating lease liability, long-term	8,064	11,751
Liability for uncertain tax positions	26,089	26,901
Minimum pension obligation and unfunded pension liability	24,620	21,545
Deferred income taxes	1,030	1,726
Other long-term liabilities	10,434	10,510
Total liabilities	268,067	300,866
Commitments and contingencies
Stockholders' equity:
Preferred stock, no par value, 1,000,000 shares authorized; none issued	0	0
Additional paid-in capital	36,136	33,826
Retained earnings	166,491	157,063
Accumulated other comprehensive loss	(18,063)	(24,065)
Total stockholders' equity	185,799	168,051
Total liabilities and stockholders' equity	453,866	468,917
Common Class A [Member]
Stockholders' equity:
Common stock	214	214
Common Class B [Member]
Stockholders' equity:
Common stock	$ 1,021	$ 1,013