Net Income (Loss) per Share - Anti-Dilutive Securities (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded as anti-dilutive (shares)	7,494	2,222	7,494	5,444
Shares of common stock issuable pursuant to 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)	7,494	2,149	7,494	5,371
Shares of common stock issuable upon exercise of outstanding warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded as anti-dilutive (shares)	0	73	0	73