CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Net earnings	$ 73,255	$ 80,192	$ 82,114
Adjustments to reconcile net earnings to cash provided by operating activities:
Depreciation	25,493	22,749	19,071
Amortization expense (including deferred financing fees)	9,841	3,954	3,954
Provision (benefit) for deferred taxes	4,846	(19,634)	26,016
Loss on extinguishment of debt	1,445	0	0
Change in fair value of acquisition related contingent consideration	(350)	0	0
Inventory obsolescence	1,654	1,882	2,376
Loss on disposal of property, plant and equipment	2,667	212	5
Unrealized foreign currency losses	533	1,297	827
Stock-based compensation	9,211	9,658	10,469
Non-cash write-off of property, plant and equipment	278	16,306	0
Bad debt and customer claims	123	1,616	6,303
Changes in assets and liabilities, net of effects of acquisitions:
Customer receivables	(24,977)	(5,500)	26,591
Inventories	(16,173)	(4,045)	(2,157)
Accounts payable	12,455	12,120	4,591
Current income taxes	2,621	(7,011)	(6,871)
Prepaid and other current assets	(3,513)	(3,350)	(13,815)
Other current liabilities	11,386	(4,813)	(3,430)
Other noncurrent assets and liabilities	(2,587)	(1,899)	(51,749)
Cash provided by operating activities	108,208	103,734	104,295
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(40,289)	(40,587)	(40,105)
Purchase of businesses, net of cash acquired	(307,983)	0	(18,456)
Cash used in investing activities	(348,272)	(40,587)	(58,561)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from revolving credit facility	490,500	310,000	377,500
Repayment of revolving credit facility	(383,000)	(338,000)	(379,500)
Proceeds from term loans	350,247	0	0
Repayment of term loans	(177,937)	0	0
Payment of financing fees	(4,652)	0	0
Payment of fees related to debt extinguishment	1,023	0	0
Payment of dividends	(29,984)	(30,193)	(29,217)
Proceeds from the issuance of common stock	64	601	2,847
Purchase of common stock for treasury	(4,411)	(10,950)	(5,464)
Contingent purchase price payment	0	(6,000)	(5,000)
Cash provided by (used in) financing activities	239,804	(74,542)	(38,834)
Effect of exchange rate changes on cash and cash equivalents	(383)	3,744	(1,238)
Net (decrease) increase in cash and cash equivalents	(643)	(7,651)	5,662
Cash and cash equivalents at beginning of year	2,203	9,854	4,192
Cash and cash equivalents at end of year	1,560	2,203	9,854
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 18,334	$ 7,605	$ 5,228