Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 2,450	$ 3,835
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	1,626	1,358
Provision for bad debts - accounts receivable	157	146
Share-based compensation expense	1,052	842
Deferred income tax provision (benefit)	162	(320)
Gain on sale of property, plant and equipment		(1,018)
Change in fair value of acquisition-related contingent liabilities	209	44
Changes in assets and liabilities:
Accounts receivable - trade	2,147	7,164
Accounts receivable - other	(259)	689
Contract assets	(3,780)
Inventories	3,742	(1,078)
Prepaid expenses and other current assets	27	(1,892)
Other assets	(1,564)	(1,522)
Accounts payable and other current liabilities	(7,132)	(1,016)
Long-term pension liability	97	(920)
Other long-term liabilities	450	696
Net cash (used in) provided by operating activities	(616)	7,008
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to property, plant and equipment	(1,055)	(930)
Proceeds from disposals of property, plant and equipment		2,808
Net cash (used in) provided by investing activities	(1,055)	1,878
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	31,657	71,209
Repayment of long-term debt	(24,642)	(71,367)
Payment of cash dividends	(1,402)	(1,231)
Payment of acquisition-related contingent liability	(2,000)	(1,800)
Proceeds received on exercise of stock options	257	105
Tax withholding on exercise of stock rights	(17)	(201)
Net cash provided by (used in) financing activities	3,958	(3,215)
Effect of currency exchange rates on cash	25	52
Net increase in cash and cash equivalents	2,312	5,723
Cash and cash equivalents balance, beginning of year	8,130	3,649
Cash and cash equivalents balance, end of period	10,442	9,372
Restricted Stock [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
Tax benefit from vesting of acquisition-related restricted stock	$ 105	$ 70