Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 60,032	$ 80,017	$ 41,626
Adjustments to reconcile net income to net cash provided by operations:
Impairment charges	443		225
Depreciation and amortization	32,821	28,971	27,010
Stock-based compensation expense	7,103	4,535	3,876
Provision for deferred income taxes	1,358	26,623	18,030
Net provision for doubtful accounts	1,709	2,400	478
Loss (gain) on sale of assets	724	630	(257)
Decrease (increase) in receivables	23,565	(135,303)	(75,829)
Increase in inventories	(28,758)	(48,129)	(8,085)
(Increase) decrease in other assets	(641)	(434)	1,898
Increase in accounts payable	13,702	30,425	2,810
(Decrease) increase in accrued liabilities and other	(1,813)	(3,293)	19,694
Net cash provided by (used in) operating activities	110,245	(13,558)	31,476
Cash flows from investing activities:
Capital expenditures	(43,955)	(36,897)	(12,134)
Proceeds from sale of property, plant and equipment	863	522	1,585
Business acquisitions, net of cash acquired	(53,075)	(26,775)
Net cash used in investing activities	(96,167)	(63,150)	(10,549)
Cash flows from financing activities:
Borrowings on lines of credit	364,426	27,619	141,497
Payments on lines of credit	(296,944)	(9,951)	(231,613)
Principal payments on notes payable and long-term debt	(40)	(219)	(30,457)
Proceeds from senior notes, net of offering costs			167,756
Proceeds from employee stock plans	1,059	3,588	3,591
Post-closing payment for business acquisition	(11,892)	(2,055)
Purchase of treasury stock	(50,756)	(644)	(153)
Net cash provided by financing activities	5,853	18,338	50,621
Effect of exchange rate changes on cash	1,668	607	(72)
Net increase (decrease) in cash and cash equivalents	21,599	(57,763)	71,476
Cash and cash equivalents at beginning of year	25,247	83,010	11,534
Cash and cash equivalents at end of year	46,846	25,247	83,010
Cash paid for:
Income taxes (net of refunds)	24,508	29,675	7,395
Interest	$ 8,355	$ 7,794	$ 7,956