Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net earnings	$ 46,142	$ 40,893
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	24,463	25,294
Stock compensation expense	5,914	4,501
Deferred income taxes	54	386
Provision for doubtful accounts	(25)	329
Unrealized (gain)/loss on foreign currency transaction and deferred compensation	(401)	30
Asset impairment charge	0	1,915
(Gain)/Loss on disposal of assets	(19)	37
Changes in assets and liabilities
Accounts receivable	(16,361)	(4,164)
Inventories	(7,949)	2,339
Prepaid expenses and other current assets	(2,859)	(1,970)
Accounts payable and accrued expenses	25,873	(9,191)
Income taxes	898	7,404
Other	659	(623)
Net cash provided by operating activities	76,389	67,180
Cash flows from investing activities:
Capital expenditures and intangible assets acquired	(13,760)	(13,265)
Proceeds from sale of assets	240	22
Purchase of convertible note	0	(350)
Net cash used in investing activities	(13,520)	(13,593)
Cash flows from financing activities:
Proceeds from revolving loan	5,000	10,000
Principal payments on revolving loan	(45,000)	(40,000)
Principal payments on finance lease	(78)	0
Proceeds from stock options exercised	3,886	6,802
Dividends paid	(18,700)	(16,704)
Purchase of treasury stock	(10,835)	(3,025)
Net cash used in financing activities	(65,727)	(42,927)
Effect of exchange rate changes on cash	(1,811)	75
(Decrease) increase in cash and cash equivalents	(4,669)	10,735
Cash and cash equivalents beginning of period	84,571	65,672
Cash and cash equivalents end of period	$ 79,902	$ 76,407