Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net income	$ 20,352	$ 16,920
Adjustments to reconcile net income to cash flows provided by operating activities:
Depreciation and amortization	10,016	8,457
Stock-based compensation expense	2,209	1,831
Deferred taxes	385
Other non-cash items	162	(754)
Changes in assets and liabilities, net of business acquisitions:
Accounts receivable, net	(31,160)	(28,718)
Inventories	(12,623)	(11,959)
Prepaid expenses and other assets	(1,926)	(953)
Accounts payable, accrued expenses and other liabilities	22,991	32,898
Net cash flows provided by operating activities	10,406	17,722
Cash flows from investing activities:
Capital expenditures	(10,543)	(4,471)
Acquisitions of businesses	(7,250)	(21,400)
Purchase of short-term investments		(12,992)
Proceeds from maturity of short-term investments	5,000	15,000
Other investing activities	142	782
Net cash flows used for investing activities	(12,651)	(23,081)
Cash flows from financing activities:
Exercise of stock options and deferred stock units	504	70
Other financing activities	(365)	(3)
Net cash flows provided by financing activities	139	67
Net decrease in cash	(2,106)	(5,292)
Cash and cash equivalents at beginning of period	38,880	52,365
Cash and cash equivalents at end of period	36,774	47,073
Supplemental disclosure of cash flow information:
Interest	138	161
Income taxes, net of refunds	$ 12,558	$ 8,752