Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net income	$ 67,847	$ 48,098	$ 41,521
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,498	14,384	15,204
Deferred income taxes	5,433	1,024	3,574
Stock-based compensation	4,788	4,861	4,807
(Gain) Loss on disposal of property, plant and equipment	(185)	649	158
Excess tax benefits from stock compensation		(3,147)	(12,898)
Other non-cash adjustments	(284)	(271)	(245)
Changes in operating assets and liabilities:
Accounts receivable	(653)	(10,995)	867
Inventories	(5,442)	643	(1,319)
Prepaid expenses and other assets	(4,256)	905	(624)
Accounts payable	(6,966)	(2,317)	5,159
Accrued expenses and other liabilities	9,403	7,554	(7,535)
Income taxes receivable/payable	1,110	1,246	9,973
Net cash provided by operating activities	85,293	62,634	58,642
Investing Activities
Expenditures for property, plant and equipment	(14,551)	(23,333)	(12,974)
Proceeds from sales of property, plant and equipment	4,349	35	66
Purchase of acquired company, net of cash acquired		(31)	(44)
Notes receivable, net			79
Net cash used in investing activities	(10,202)	(23,329)	(12,873)
Financing Activities
Financing costs	(485)	(3)	(453)
Borrowings under line of credit	242,700	225,500	143,000
Principal payments under line of credit	(249,700)	(218,500)	(143,000)
Repurchases of common stock	(55,216)	(53,313)	(53,189)
Proceeds from employee stock purchase and option plans	279	315	747
Excess tax benefits from stock compensation		3,147	12,898
Net cash used in financing activities	(62,422)	(42,854)	(39,997)
Net increase (decrease) in cash and cash equivalents	12,669	(3,549)	5,772
Cash and cash equivalents at beginning of year	5,995	9,544	3,772
Cash and cash equivalents at end of year	18,664	5,995	9,544
Supplemental disclosures of cash flow information:
Cash paid for interest	852	625	520
Cash paid for income taxes, net	$ 28,626	$ 26,327	$ 11,919