Summary of Significant Accounting Policies (Details 3) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
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									1,563,417		3,230,705
Net income (loss) per share
Income (loss) available to common stockholders (in dollars)	$ (14,818)	$ (8,718)	$ (471)	$ (10,027)	$ (2,113)	$ 1,151	$ 4,227	$ 1,812	$ (34,034)	$ 5,077	$ (17,573)
Weighted average common shares outstanding used in computing basic net income (loss) per share									107,619,000	106,234,000	104,522,000
Incremental shares										2,864,000
Weighted average common shares outstanding used in computing diluted net income (loss) per share									107,619,000	109,098,000	104,522,000
Net income (loss) per share
Basic (in dollars per share)									$ (0.32)	$ 0.05	$ (0.17)
Diluted (in dollars per share)									$ (0.32)	$ 0.05	$ (0.17)