Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net earnings	$ 23,411	$ 19,768
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	12,364	12,549
Stock compensation expense	2,622	2,181
Deferred income taxes	0	135
Provision for doubtful accounts	69	522
Unrealized gain on foreign currency transactions and deferred compensation	(230)	(23)
Changes in assets and liabilities
Accounts receivable	(9,610)	(13,516)
Inventories	(6,702)	528
Prepaid expenses and other current assets	1,000	(349)
Accounts payable and accrued expenses	10,344	(3,098)
Income taxes	7,043	4,523
Other	296	(655)
Net cash provided by operating activities	40,607	22,565
Cash flows from investing activities:
Capital expenditures and intangible assets acquired	(6,312)	(5,394)
Proceeds from sale of assets	86	0
Net cash used in investing activities	(6,226)	(5,394)
Cash flows from financing activities:
Proceeds from revolving loan	5,000	10,000
Principal payments on revolving loan	(15,000)	(5,000)
Principal payments on finance lease	(39)	0
Proceeds from stock options exercised	2,402	4,435
Dividends paid	(18,700)	(16,704)
Purchase of treasury stock	(1,596)	(891)
Net cash used in financing activities	(27,933)	(8,160)
Effect of exchange rate changes on cash	(2,484)	(724)
Increase in cash and cash equivalents	3,964	8,287
Cash and cash equivalents beginning of period	84,571	65,672
Cash and cash equivalents end of period	$ 88,535	$ 73,959