Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 13,038	$ 14,508	$ 18,808
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,731	2,799	2,175
Stock based compensation	2,936	2,160	1,917
Loss on disposal of property and equipment	8	3	107
Provision for (recovery of) inventory valuation	38	(30)	(84)
Deferred tax assets	(158)	2,346	(2,334)
Changes in assets and liabilities:
Accounts receivable	(1,300)	760	(3,520)
Inventories	(2,066)	1,355	(3,613)
Prepaid expenses and other current assets	(609)	(332)	(579)
Other assets	(1)	(14)	51
Accounts payable	(2,830)	(2,421)	5,066
Accrued expenses and other current liabilities	725	1,565	3,019
Long-term liabilities	1,554	378	(16)
Net cash provided by operating activities	14,066	23,077	20,997
Cash flows from investing activities:
Purchase of short-term investments	(57,752)	(35,438)	(21,492)
Proceeds from sales and maturities of short-term investments	71,055	31,643	21,908
Purchase of long-term investments	(186)	(182)	(179)
Purchase of property and equipment	(5,587)	(3,980)	(7,830)
Net cash provided by (used in) investing activities	7,530	(7,957)	(7,593)
Cash flows from financing activities:
Proceeds from issuance of common stock under ESPP	673	661	521
Proceeds from the exercise of stock options	669	607	5,239
Tax payments related to net share settlements of RSUs	732	501	(1,326)
Repurchase of common stock	$ (40,172)	(9,676)	(873)
Payment of dividends		(2,700)	(2,761)
Net cash (used in) provided by financing activities	$ (38,098)	(10,607)	800
Effect of exchange rate changes on cash and cash equivalents	(64)	(393)	(394)
Net (decrease) increase in cash and cash equivalents	(16,566)	4,120	13,810
Cash and cash equivalents at beginning of year	22,723	18,603	4,793
Cash and cash equivalents at end of year	6,157	22,723	18,603
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ (3,385)	$ (1,092)	$ (433)