Computation of Net Loss per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Computation of Net Loss per Share
Net loss attributable to common stockholders (in dollars)	$ (6,900)	$ (4,019)	$ (6,726)	$ (13,008)
Weighted average common shares outstanding used in computing basic and diluted net loss per share	111,212	108,409	110,932	108,319
Net loss per share
Basic and Diluted (in dollars per share)	$ (0.06)	$ (0.04)	$ (0.06)	$ (0.12)
Incremental shares excluded from the calculation of net loss per share (in shares)	4,047	2,183	4,625	2,159