Net Income (Loss) Per Share - Reconciliation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income (loss)	$ (7,168)	$ 5,785
Less: preferred stock dividends	12	70
Net income (loss) attributable to common stockholders	$ (7,180)	$ 5,715
Denominator:
Weighted-average number of shares of common stock for basic and diluted net income (loss) per share (in shares)	47,950,000	37,603,000
Add effect of dilutive securities:
Unvested RSUs/Unvested restricted stock (in shares)	0
Shares of common stock issuable upon conversion of preferred stock (in shares)	0	1,706,000
Warrants (in shares)	0	38,000
Weighted-average number of shares of common stock for diluted net income (loss) per share (in shares)	47,950,000	41,440,000
Basic net income (loss) per share (in dollars per share)	$ (0.15)	$ 0.15
Diluted net income (loss) per share (in dollars per share)	$ (0.15)	$ 0.14
RSUs
Add effect of dilutive securities:
Unvested RSUs/Unvested restricted stock (in shares)	0	1,752,000
Restricted Stock
Add effect of dilutive securities:
Unvested RSUs/Unvested restricted stock (in shares)	0	341,000