Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 14,638,000	$ 13,066,000	$ 11,349,000
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation and amortization	4,935,000	3,873,000	3,839,000
Provision for bad debts - accounts receivable	512,000	266,000	197,000
Share-based compensation expense	1,638,000	1,361,000	1,404,000
Deferred income tax (benefit) provision	(1,940,000)	(1,216,000)	1,000
Gain on foreign currency transactions	(264,000)
Gain on disposals of property, plant and equipment		(1,000)	(91,000)
Adjustment to acquisition-related contingent liability	(200,000)	(200,000)
Accretion of acquisition-related contingent liability	169,000	119,000	128,000
Excess tax benefit from exercise of stock options and SARS		1,575,000	263,000
Changes in assets and liabilities, net of acquisition of business:
Accounts receivable - trade	(7,244,000)	(2,224,000)	(5,418,000)
Accounts receivable - other	177,000	873,000	(2,000)
Inventories	(5,427,000)	(5,291,000)	(8,796,000)
Prepaid expenses and other current assets	2,203,000	(1,717,000)	1,515,000
Other assets	(1,029,000)	(1,817,000)	(15,000)
Accounts payable	87,000	2,069,000	1,343,000
Other current liabilities	1,943,000	(631,000)	1,180,000
Long-term pension liability	829,000	(112,000)	216,000
Other long-term liabilities	962,000	(80,000)	(45,000)
Net cash provided from operating activities	11,989,000	9,913,000	7,068,000
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to property, plant and equipment	(7,385,000)	(8,069,000)	(4,936,000)
Proceeds from disposals of property, plant and equipment		24,000	128,000
Acquisition of business, net of acquired cash	(15,161,000)
Net cash used in investing activities	(22,546,000)	(8,045,000)	(4,808,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	125,067,000	67,345,000	55,150,000
Repayment of long-term debt	(106,827,000)	(68,416,000)	(56,332,000)
Payment of cash dividends	(4,707,000)	(4,255,000)	(3,663,000)
Payment of acquisition-related contingent liability	(1,800,000)	(1,200,000)
Proceeds received on exercise of stock options	1,504,000	1,840,000	1,855,000
Common stock reqcquired and retired	(714,000)
Net cash provided from (used in) financing activities	13,108,000	(5,418,000)	(2,990,000)
Effect of exchange rates on cash	62,000
Net increase (decrease) in cash and cash equivalents	2,613,000	(3,550,000)	(730,000)
Cash and cash equivalents balance, beginning of year	1,036,000	4,586,000	5,316,000
Cash and cash equivalents balance, end of year	3,649,000	1,036,000	4,586,000
Restricted Stock [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Tax benefit from vesting of acquisition related restricted stock	990,000
Stock Appreciation Rights (SARs) [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Tax withholdings on exercise of stock rights	$ (405,000)	$ (732,000)