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 (loss)	$ 18,244	$ 14,738	$ (7,040)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	5,131	6,519	8,097
Loss on impairment			1,354
(Gain) loss on write down / disposal of property and equipment, net	(27)	161	2,800
Loss on disposal of intangibles	168	195	54
Bond premium amortization	289	29	371
Provision (recovery) for doubtful accounts	24	(242)	296
Provision for excess and obsolete inventory	595	554	4,610
Provision for warranty	1,001	527	310
Stock-based compensation expense	4,340	3,422	3,038
Deferred income taxes	621	1,683	(2,481)
Provision for unrecognized tax benefits	219	920	(299)
Excess tax benefit from stock-based compensation	(6,797)	(4,713)	(10)
Change in assets and liabilities:
Accounts and notes receivable	(4,411)	(6,080)	1,463
Inventory	(711)	(62)	1,328
Prepaid expenses and other current assets	(569)	177	(374)
Accounts payable and accrued liabilities	5,559	4,433	3,412
Deferred revenue	8,096	4,169	296
Customer deposits	654	87	41
Net cash provided by operating activities	32,426	26,517	17,266
Cash flows from investing activities:
Purchases of investments	(29,112)	(6,242)	(11,479)
Proceeds from call / maturity of investments	9,380	9,640	6,000
Purchases of property and equipment	(1,783)	(1,334)	(1,854)
Proceeds from disposal of fixed assets	34	46	149
Purchases of intangible assets	(323)	(429)	(413)
Business acquisition, net of cash acquired	(1,258)
Net cash (used in) provided by investing activities	(23,062)	1,681	(7,597)
Cash flows from financing activities:
Repurchase of common stock	(25,000)	(19,996)	(32,499)
Proceeds from options exercised	15,357	1,929	1,427
Payroll tax payments for net-settled stock awards	(309)
Payments on capital lease obligation	(34)	(9)
Excess tax benefit from stock-based compensation	6,797	4,713	10
Net cash used in financing activities	(3,189)	(13,363)	(31,062)
Effect of exchange rate changes on cash and cash equivalents	(31)	(9)	10
Net increase (decrease) in cash and cash equivalents	6,144	14,826	(21,383)
Cash and cash equivalents, beginning of year	36,127	21,301	42,684
Cash and cash equivalents, end of year	$ 42,271	$ 36,127	$ 21,301