Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 15,022	$ 14,638	$ 13,066
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation and amortization	5,653	4,935	3,873
Provision for bad debts - accounts receivable	1,002	512	266
Share-based compensation expense	1,664	1,638	1,361
Deferred income tax provision (benefit)	5,114	(1,940)	(1,216)
Gain on foreign currency transactions		(264)
Gain on disposals of property, plant and equipment	(1,048)		(1)
Adjustment to acquisition-related contingent liability	(250)	(200)	(200)
Accretion of acquisition-related contingent liability	161	169	119
Excess tax benefit from exercise of stock options and SARS			1,575
Changes in assets and liabilities, net of acquisition of businesses:
Accounts receivable - trade	(4,731)	(7,244)	(2,224)
Accounts receivable - other	1,237	177	873
Inventories	4,250	(5,427)	(5,291)
Prepaid expenses and other current assets	(4,151)	2,203	(1,717)
Other assets	(4,504)	(1,029)	(1,817)
Accounts payable	3,291	87	2,069
Other current liabilities	71	1,943	(631)
Long-term pension liability	(2,577)	829	(112)
Other long-term liabilities	2,523	962	(80)
Net cash provided from operating activities	22,727	11,989	9,913
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to property, plant and equipment	(4,248)	(7,385)	(8,069)
Proceeds from disposals of property, plant and equipment	2,858		24
Acquisition of businesses, net of acquired cash	(7,988)	(15,161)
Net cash used in investing activities	(9,378)	(22,546)	(8,045)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	74,387	125,067	67,345
Repayment of long-term debt	(77,573)	(106,827)	(68,416)
Payment of cash dividends	(5,269)	(4,707)	(4,255)
Payment of acquisition-related contingent liability	(1,800)	(1,800)	(1,200)
Proceeds received on exercise of stock options	1,872	1,504	1,840
Tax withholdings on exercise of stock rights	(1,186)	(405)	(732)
Common stock reqcquired and retired		(714)
Net cash (used in) provided from financing activities	(8,919)	13,108	(5,418)
Effect of exchange rates on cash	51	62
Net increase (decrease) in cash and cash equivalents	4,481	2,613	(3,550)
Cash and cash equivalents balance, beginning of year	3,649	1,036	4,586
Cash and cash equivalents balance, end of year	8,130	3,649	1,036
Restricted Stock [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Tax benefit from vesting of acquisition related restricted stock	$ 650	$ 990