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 earnings	$ 80,192	$ 82,114	$ 65,948
Adjustments to reconcile net earnings to cash provided by operating activities:
Depreciation	22,749	19,071	17,364
Amortization expense (including deferred financing fees)	3,954	3,954	3,915
Provision for deferred taxes	(19,634)	26,016	158
Inventory obsolescence	1,882	2,376	2,656
Loss on disposal of property, plant and equipment	212	5	1,229
Unrealized foreign currency losses (gains)	1,297	827	(8,789)
Stock-based compensation	9,658	10,469	8,166
Intangible asset impairment charge	0	0	10,650
Non-cash write-off of property, plant and equipment	16,306	0	0
Bad debt and customer claims	1,616	6,303	1,477
Changes in assets and liabilities, net of effects of acquisitions:
Customer receivables	(5,500)	26,591	(4,292)
Inventories	(4,045)	(2,157)	(4,481)
Accounts payable	12,120	4,591	(26,253)
Current income taxes	(7,011)	(6,871)	675
Prepaid and other current assets	(3,350)	(13,815)	(5,425)
Other current liabilities	(4,813)	(3,430)	22,937
Other noncurrent assets and liabilities	(1,899)	(51,749)	2,919
Cash provided by operating activities	103,734	104,295	88,854
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(40,587)	(40,105)	(29,610)
Purchase of businesses, net of cash acquired	0	(18,456)	0
Cash used in investing activities	(40,587)	(58,561)	(29,610)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from credit facility	310,000	377,500	309,000
Repayment of credit facility	(338,000)	(379,500)	(345,000)
Payment of financing fees	0	0	(10)
Payment of dividends	(30,193)	(29,217)	(24,364)
Proceeds from the issuance of common stock	601	2,847	5,756
Purchase of common stock for treasury	(10,950)	(5,464)	(8,725)
Contingent purchase price payment	(6,000)	(5,000)	(5,000)
Tax benefit from the exercise of stock options and vesting of equity awards	0	0	826
Cash used in financing activities	(74,542)	(38,834)	(67,517)
Effect of exchange rate changes on cash and cash equivalents	3,744	(1,238)	(6,556)
Net (decrease) increase in cash and cash equivalents	(7,651)	5,662	(14,829)
Cash and cash equivalents at beginning of year	9,854	4,192	19,021
Cash and cash equivalents at end of year	2,203	9,854	4,192
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 7,605	$ 5,228	$ 6,168