Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES:
Net income (loss)	$ 23,377	$ 11,068	$ (10,582)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	6,712	6,326	5,530
Compensation for stock options and restricted stock units	2,727	2,392	2,449
Provision for bad debts	2,169	2,408	1,852
Deferred income tax expense (benefit)	(672)	(693)	1,986
Change in operating assets and liabilities:
Accounts receivable	(8,979)	(13,018)	5,769
Inventories, net	(27,329)	(6,273)	8,301
Prepaid expenses and other current assets	(1,417)	(2,172)	1,964
Income tax benefit from exercise of stock options	(1,593)	(133)	(4)
Increase (decrease) in:
Accounts payable and accrued liabilities	4,644	10,435	(7,891)
Income taxes payable	2,998	829	(1,749)
Customer deposits	668	1,474	1,736
Unearned service revenues	5,384	2,338	(396)
Net cash provided by operating activities	8,689	14,981	8,965
INVESTING ACTIVITIES:
Purchases of property and equipment	(4,474)	(4,047)	(3,387)
Payments for intangible assets	(890)	(979)	(670)
Purchases of short-term investments			(64,986)
Proceeds from sales of short-term investments			81,965
Net cash (used in) provided by investing activities	(5,364)	(5,026)	12,922
FINANCING ACTIVITIES:
Proceeds from notes payable		2,490
Payments on notes payable		(2,490)
Payments on capital leases	(163)	(84)	(88)
Income tax benefit from exercise of stock options	1,593	133	4
Purchases of treasury stock			(8,829)
Proceeds from issuance of stock, net	9,150	1,405	83
Net cash provided by (used in) financing activities	10,580	1,454	(8,830)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(87)	4,235	(1,473)
INCREASE IN CASH AND CASH EQUIVALENTS	13,818	15,644	11,584
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	50,722	35,078	23,494
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 64,540	$ 50,722	$ 35,078