Stockholders' Equity - Summary of Warrants Activity (Details) - Warrant - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Number of Warrants
Outstanding and exercisable at January 1, 2019 (in shares)	1,214,815
Granted (in shares)	0
Canceled (in shares)	0
Exercised (in shares)	0
Expired/Forfeited (in shares)	0
Outstanding and exercisable at June 30, 2019 (in shares)	1,214,815	1,214,815
Weighted Average Exercise Price
Outstanding and exercisable at January 1, 2019 (in dollars per share)	$ 9.32
Granted (in dollars per share)	0.00
Canceled (in dollars per share)	0.00
Exercised (in dollars per share)	0.00
Expired/Forfeited (in dollars per share)	0.00
Outstanding and exercisable at June 30, 2019 (in dollars per share)	$ 9.32	$ 9.32
Weighted Average Remaining Contractual Life (in Years), Outstanding and exercisable	1 year 1 month 28 days	1 year 7 months 28 days
Aggregate Intrinsic Value, Outstanding and exercisable	$ 0	$ 0