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	$ 90,071	$ 55,972	$ 59,722
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	44,379	46,202	39,964
Stock compensation expense	6,264	7,024	6,829
Deferred income taxes	(28,777)	(6,881)	(2,857)
Provision for doubtful accounts	69	258	(53)
Foreign currency transaction loss	340	(16)	25
Loss on disposal of assets	254	320	301
Changes in assets and liabilities, net of acquired balances
Accounts receivable	(3,906)	(15,659)	10,809
Inventories	(319)	4,745	3,126
Prepaid expenses and other current assets	(439)	240	1,233
Accounts payable and accrued expenses	1,511	17,841	(15,718)
Income taxes	449	(2,765)	633
Other	722	331	(188)
Net cash provided by operating activities	110,618	107,612	103,826
Cash flows from investing activities:
Capital expenditures	(27,526)	(23,034)	(41,300)
Cash paid for acquisitions, net of cash acquired	(17,393)	(110,601)	0
Proceeds from sale of property, plant and equipment	22	4	34
Proceeds from insurance	2,792	1,000	0
Intangible assets acquired	(591)	(963)	(1,011)
Net cash used in investing activities	(42,696)	(133,594)	(42,277)
Cash flows from financing activities:
Principal payments on long-term debt	(43,000)	(35,000)	(35,000)
Proceeds from revolving loan	25,000	72,500	0
Principal payments on revolving loan	(44,000)	(53,500)	0
Principal payment on acquired debt	(2,384)	(884)	0
Proceeds from stock options exercised	9,732	7,192	12,605
Excess tax benefits from stock compensation	0	2,546	7,009
Dividends paid	(12,069)	(10,720)	(9,251)
Purchase of treasury stock	(1,905)	(1,588)	(1,205)
Net cash used in by financing activities	(68,626)	(19,454)	(25,842)
Effect of exchange rate changes on cash	2,477	(716)	(1,199)
Increase/(Decrease) in cash and cash equivalents	1,773	(46,152)	34,508
Cash and cash equivalents beginning of period	38,643	84,795	50,287
Cash and cash equivalents end of period	$ 40,416	$ 38,643	$ 84,795