Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 8,372	$ 11,116
Adjustments to reconcile net income to cash flows provided by operating activities:
Depreciation and amortization	6,552	6,381
Stock-based compensation expense	3,155	1,319
Other non-cash items	509	461
Changes in assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net	(32,403)	(34,915)
Inventories	(12,840)	3,939
Prepaid expenses and other assets	3,880	(510)
Accounts payable	18,531	4,007
Accrued expenses and other liabilities	3,192	11,362
Net cash flows (used for) provided by operating activities	(1,052)	3,160
Cash flows from investing activities:
Capital expenditures	(8,938)	(5,684)
Acquisitions of businesses		(1,164)
Proceeds from sales of fixed assets	31	44
Other investing activities	(29)	(19)
Net cash flows used for investing activities	(8,936)	(6,823)
Cash flows from financing activities:
Exercise of stock options and deferred stock units	4,959	974
Proceeds from line of credit borrowings	96,333	37,702
Repayments under line of credit borrowings	(96,333)	(37,702)
Payment of contingent consideration related to acquisitions	(875)	(354)
Net cash flows provided by financing activities	4,084	620
Net decrease in cash	(5,904)	(3,043)
Cash and cash equivalents at beginning of period	9,939	6,584
Cash and cash equivalents at end of period	4,035	3,541
Supplemental disclosure of cash flow information:
Interest	64	96
Income taxes, net of refunds	$ 16	$ (9)