Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 41,026	$ 12,066	$ 16,975
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,132	8,272	7,906
Provision for bad debts - accounts receivable	6,746	1,323	867
Share-based compensation expense	2,530	1,484	2,264
Deferred income tax benefit	(4,987)	(1,595)	(665)
Gain on sale of property, plant and equipment	(2,164)	(5)	0
Change in fair value of acquisition-related contingent liabilities	4,119	(74)	(1,116)
Changes in assets and liabilities, net of acquisition of business:
Accounts receivable	(29,251)	(17,104)	(4,886)
Accounts receivable - other	(273)	660	105
Contract assets	(699)	10,703	(3,382)
Inventories	(16,763)	(4,984)	2,429
Prepaid expenses and other current assets	(1,474)	(3,479)	2,622
Other assets	464	(1,717)	(1,257)
Accounts payable and other current liabilities	32,690	10,904	(1,344)
Long-term pension liability	(508)	2,138	(128)
Other long-term liabilities	1,771	1,415	(526)
Net cash provided by operating activities	41,359	20,007	19,864
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to property, plant and equipment	(11,857)	(9,672)	(4,869)
Proceeds from disposals of property, plant and equipment	5,284	5	0
Acquisition of businesses, net of acquired cash	0	0	(85,597)
Net cash used in investing activities	(6,573)	(9,667)	(90,466)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from borrowings of debt	202,349	165,314	206,025
Repayment of debt	(234,063)	(163,645)	(127,439)
Payment of cash dividends	(6,111)	(6,046)	(5,836)
Payment of acquisition-related contingent liabilities	(1,966)	(961)	(2,861)
Proceeds received on exercise of stock options	1,927	283	727
Tax withholdings on exercise of stock rights	(66)	0	(17)
Tax (provision) benefit from vesting of acquisition-related restricted stock	(13)	30	445
Common stock reacquired and retired	(500)	(1,685)	(2,906)
Net cash provided by (used in) financing activities	(38,443)	(6,710)	68,138
Effect of currency exchange rates on cash	(209)	46	(304)
Net increase (decrease) in cash and cash equivalents	(3,866)	3,676	(2,768)
Cash and cash equivalents balance, beginning of period	9,038	5,362	8,130
Cash and cash equivalents balance, end of period	5,172	9,038	5,362
Supplemental disclosure of cash flow information:
Income taxes paid	13,390	7,146	1,088
Interest paid	$ 1,490	$ 3,979	$ 2,724