Net Loss per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded as anti-dilutive (shares)	7,734	6,650
Equity awards outstanding under the Equity Incentive Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded as anti-dilutive (shares)	7,661	6,577
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded as anti-dilutive (shares)	73	73