Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 3,036	$ 6,190
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	2,759	2,394
Depreciation and amortization	922	757
Loss on disposal of fixed assets		4
Provision (release) of allowance for doubtful accounts	22	(52)
Changes in operating assets and liabilities:
Accounts receivable	2,887	(777)
Inventories	657	903
Prepaid expenses and other assets	301	205
Accounts payable	(1,355)	316
Accrued liabilities and long-term liabilities	(1,149)	208
Net cash provided by operating activities	8,080	10,148
Cash flows from investing activities:
Purchases of property and equipment	(966)	(422)
Purchases of short-term investments	(3,000)	(2,000)
Proceeds from maturity of short-term investments	2,000
Cash paid for acquisitions, net	(3,861)
Net cash used in investing activities	(5,827)	(2,422)
Cash flows from financing activities:
Proceeds from issuance of common stock, net	695	6,680
Repurchase of common stock	(1,875)	(997)
Taxes paid related to net share settlement of equity awards	(55)	(64)
Net cash provided by financing activities	(1,235)	5,619
Net increase in cash and cash equivalents	1,018	13,345
Cash and cash equivalents, beginning of period	148,364	126,733
Cash and cash equivalents, end of period	149,382	140,078
Supplemental disclosure of cash flows:
Cash paid for income taxes	$ 26	$ 57