Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net earnings	$ 62,461	$ 59,288
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	38,349	33,485
Stock compensation expense	6,755	5,717
Deferred income taxes	532	(198)
Provision for doubtful accounts	250	896
Foreign currency transaction loss	153	21
Asset impairment charge	1,915	114
Loss/(gain) on disposal of assets	57	(3,220)
Changes in assets and liabilities
Accounts receivable	(4,979)	8,340
Inventories	6,802	(6,017)
Prepaid expenses and other current assets	(844)	(784)
Accounts payable and accrued expenses	(6,978)	(145)
Income taxes	(1,957)	(5,955)
Other	24	(48)
Net cash provided by operating activities	102,540	91,494
Cash flows from investing activities:
Cash paid for acquisition, net of cash acquired	0	(94,690)
Capital expenditures and intangible assets acquired	(20,552)	(21,669)
Proceeds from insurance	0	2,727
Proceeds from sale of assets	22	11,523
Purchase of convertible notes	(850)	(1,000)
Net cash used in investing activities	(21,380)	(103,109)
Cash flows from financing activities:
Proceeds from revolving loan	10,000	123,569
Principal payments on revolving loan	(65,000)	(61,000)
Principal payments on finance lease	(112)	0
Principal payments on acquired debt	0	(12,222)
Proceeds from stock options exercised	8,179	3,734
Dividends paid	(16,704)	(15,135)
Purchase of treasury stock	(5,982)	(21,321)
Net cash (used in) provided by financing activities	(69,619)	17,625
Effect of exchange rate changes on cash	1,754	(874)
Increase in cash and cash equivalents	13,295	5,136
Cash and cash equivalents beginning of period	65,672	54,268
Cash and cash equivalents end of period	$ 78,967	$ 59,404