Net Loss Per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	43,138	36,000
Employee and non-employee stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	9,402	6,660
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	840	435
Common Stock Subject to Repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	1,499	1,857
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in the calculation of diluted EPS	31,397	27,048