Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating Activities
Net income	$ 27,456	$ 34,793
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,660	8,341
Deferred income taxes		(346)
Stock-based compensation	2,455	1,797
(Gain) loss on disposal of property, plant and equipment	(48)	220
Excess tax benefits from stock compensation	(12,533)
Other non-cash adjustments	(245)	(337)
Changes in operating assets and liabilities:
Accounts receivable	(22,794)	(24,411)
Inventories	1,373	2,557
Prepaid expenses and other assets	(206)	482
Accounts payable	4,583	3,859
Accrued expenses and other liabilities	(6,007)	(4,080)
Income taxes receivable/payable	9,764	265
Net cash provided by operating activities	11,458	23,140
Investing Activities
Expenditures for property, plant and equipment	(4,927)	(5,110)
Proceeds from sales of property, plant and equipment	48	174
Purchase of acquired company, net of cash acquired	(44)
Notes receivable, net	39	63
Net cash used in investing activities	(4,884)	(4,873)
Financing Activities
Financing costs		(73)
Borrowings under line of credit	120,000	74,500
Principal payments under line of credit	(85,000)	(79,500)
Repurchases of common stock	(52,892)	(3,153)
Proceeds from employee stock purchase and option plans	585	3,383
Excess tax benefits from stock compensation	12,533
Net cash used in financing activities	(4,774)	(4,843)
Net increase in cash and cash equivalents	1,800	13,424
Cash and cash equivalents at beginning of period	3,772	2,159
Cash and cash equivalents at end of period	5,572	15,583
Supplemental Disclosure:
Cash paid for interest, net of capitalized interest	384	344
Cash paid for income taxes, net	$ 6,783	$ 375