CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues:
Product revenues	$ 185,864	$ 171,100	$ 170,068
Service and other revenues	59,671	51,307	43,389
Total revenues	245,535	222,407	213,457
Cost of revenues:
Cost of product revenues	79,567	76,372	80,016
Cost of service and other revenues	30,184	28,079	27,011
Restructuring charges		39	1,209
Total cost of revenues	109,751	104,490	108,236
Gross profit	135,784	117,917	105,221
Operating expenses:
Research and development	22,042	21,007	17,569
Selling, general and administrative	97,520	86,227	85,668
Restructuring charges		1,157	1,315
Total operating expenses	119,562	108,391	104,552
Income from operations	16,222	9,526	669
Interest income	266	424	619
Interest expense	(62)	(4)	(15)
Other income (expense)	(337)	11	(81)
Income before provision for income taxes	16,089	9,957	1,192
Provision for income taxes	5,700	5,065	748
Net income	$ 10,389	$ 4,892	$ 444
Net income per share-basic (in dollars per share)	$ 0.31	$ 0.15	$ 0.01
Net income per share-diluted (in dollars per share)	$ 0.30	$ 0.15	$ 0.01
Weighted average shares outstanding:
Basic (in shares)	33,123	32,651	31,691
Diluted (in shares)	34,103	33,513	32,063