Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 4,533	$ 3,580	$ 860
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for doubtful accounts	1,305	536	276
Depreciation and amortization	5,994	4,610	4,374
Deferred income taxes	(713)	2,046	(737)
(Gain) loss on derivatives instruments	(222)	128	131
Compensation expense related to stock-based awards and employee stock purchase plan	4,124	3,679	3,533
Changes in operating assets and liabilities:
Accounts receivable	1,229	(2,231)	(7,438)
Inventories	(1,967)	2,420	(3,851)
Prepaid expenses and other assets	619	(716)	164
Other non-current assets	(675)	(558)	2,028
Accounts payable	1,196	943	2,223
Deferred revenue	(124)	(785)	1,684
Accrued expenses	891	1,401	(253)
Other long-term liabilities	65	4	(1,127)
Net cash provided by operating activities	16,255	15,057	1,867
Cash flows from investing activities:
Capital expenditures	(4,720)	(6,504)	(14,064)
Net cash paid for business acquired	(22,944)	0	0
Purchases of marketable securities	(41,950)	(21,945)	(49,541)
Maturities and sales of marketable securities	24,867	16,190	56,053
Net cash used in investing activities	(44,747)	(12,259)	(7,552)
Cash flows from financing activities:
Repayments of long-term debt	(1,030)	(131)	(124)
Borrowings from long-term debt	5,844	0	0
Proceeds from stock options exercised and employee stock purchase plan	2,344	1,578	942
Repurchase of common stock	0	0	(3,679)
Payment of employee restricted stock withholdings	(828)	(332)	(625)
Repayments of line of credit borrowings	0	(2,000)	0
Proceeds from line of credit borrowings	23,000	0	9,000
Payment of stock registration fee	(5)	0	(10)
Net cash provided by (used in) financing activities	29,325	(885)	5,504
Effect of exchange rate changes on cash and cash equivalents	(453)	48	(43)
Net increase (decrease) in cash and cash equivalents	380	1,961	(224)
Cash and cash equivalents at beginning of period	8,978	7,017	7,241
Cash and cash equivalents at end of period	9,358	8,978	7,017
Supplemental disclosure of cash flow information:
Cash paid for interest	601	201	267
Cash paid for income taxes	1,248	323	58
Supplemental disclosure of noncash investing activity:
Changes in accrued liabilities related to fixed asset additions	$ 0	$ 435	$ 945