Summary of Significant Accounting Policies (Details 3) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue recognition
Maximum deferral period from shipment for recognition of systems revenue and related costs									12 months
Anti-dilutive shares excluded from calculation of net loss per share									3,547,578	1,563,417
Net income (loss) per share
Income (loss) available to common stockholders (in dollars)	$ 614	$ (4,750)	$ (4,019)	$ (8,988)	$ (14,818)	$ (8,718)	$ (471)	$ (10,027)	$ (17,144)	$ (34,034)	$ 5,077
Weighted average common shares outstanding used in computing basic net income (loss) per share									108,869,000	107,619,000	106,234,000
Incremental shares											2,864,000
Weighted average common shares outstanding used in computing diluted net income (loss) per share									108,869,000	107,619,000	109,098,000
Net income (loss) per share
Basic (in dollars per share)									$ (0.16)	$ (0.32)	$ 0.05
Diluted (in dollars per share)									$ (0.16)	$ (0.32)	$ 0.05