Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net income	$ 32,595	$ 25,971
Adjustments to reconcile net income to cash flows provided by operating activities:
Depreciation and amortization	19,211	15,069
Stock-based compensation expense	4,703	3,352
Deferred taxes		26
Other non-cash items	889	751
Changes in assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net	(27,801)	(24,440)
Inventories	(5,753)	(20,581)
Prepaid expenses and other assets	(6,993)	(1,996)
Accounts payable	17,650	18,755
Accrued expenses and other liabilities	10,086	(628)
Net cash flows provided by operating activities	44,587	16,279
Cash flows from investing activities:
Capital expenditures	(22,010)	(17,721)
Acquisitions of businesses	(1,473)	(49,340)
Proceeds from maturity of short-term investments		5,000
Proceeds from sales of fixed assets	5,397	1,248
Other investing activities	(88)	(438)
Net cash flows used for investing activities	(18,174)	(61,251)
Cash flows from financing activities:
Exercise of stock options and deferred stock units	2,840	504
Proceeds from line of credit borrowings	37,702	48,675
Repayments under line of credit	(37,702)	(40,600)
Payment of contingent consideration related to acquisitions	(3,253)	(226)
Purchase of treasury stock		(626)
Other financing activities		(163)
Net cash flows (used for) provided by financing activities	(413)	7,564
Net increase (decrease) in cash	26,000	(37,408)
Cash and cash equivalents at beginning of period	6,584	38,880
Cash and cash equivalents at end of period	32,584	1,472
Supplemental disclosure of cash flow information:
Interest	289	263
Income taxes, net of refunds	$ 16,121	$ 17,101