CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 66,852	$ 69,354
Accounts receivable, net of allowance for doubtful accounts of $1,709 in 2018 and $1,745 in 2017	76,787	78,808
Unbilled receivables	13,643	0
Inventories	102,693	107,719
Other current assets	10,004	10,218
Total current assets	269,979	266,099
Property, plant and equipment, net	43,322	43,495
Intangible assets, net	68,286	69,366
Goodwill	20,419	20,177
Deferred income taxes	4,980	4,155
Other assets	28,408	27,973
Total assets	435,394	431,265
Current Liabilities:
Accounts payable	48,169	47,947
Accrued expenses	27,409	30,508
Current portion of long-term debt	2,642	2,641
Other current liabilities	7,664	6,204
Total current liabilities	85,884	87,300
Long-term Liabilities:
Long-term debt	119,390	120,053
Liability for uncertain tax positions	28,788	27,948
Minimum pension obligation and unfunded pension liability	19,403	19,134
Deferred income taxes	1,778	1,567
Other liabilities	15,976	17,303
Total liabilities	271,219	273,305
Commitments and contingencies
Stockholders' Equity:
Preferred stock, no par value, 1,000,000 shares authorized; none issued	0	0
Additional paid-in capital	29,355	28,575
Retained earnings	149,171	147,807
Accumulated other comprehensive loss	(15,553)	(19,625)
Total stockholders' equity	164,175	157,960
Total liabilities and stockholders' equity	435,394	431,265
Class A Common Stock [Member]
Stockholders' Equity:
Common Stock	217	217
Class B Common Stock [Member]
Stockholders' Equity:
Common Stock	$ 985	$ 986