Stockholders' Equity - Summary of Option Activity under 2018 Plan, 2013 Plan and 2010 Plan (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Options
Number of Shares, Options outstanding at beginning of period	1,313,475
Number of Shares, Options Granted	61,000
Number of Shares, Options outstanding at end of period	1,374,475	1,313,475
Number of Shares, Options exercisable at end of period	447,477
Weighted Average Exercise Price, Options
Weighted Average Exercise Price, Options outstanding at beginning of period	$ 12.28
Weighted Average Exercise Price, Options Granted	3.89
Weighted Average Exercise Price, Options outstanding at end of period	11.91	$ 12.28
Weighted Average Exercise Price, Options exercisable at end of period	$ 14.39
Weighted Average Remaining Contract Term, Options
Weighted Average Remaining Contractual Term, Options outstanding at beginning of period	8 years 6 months	8 years 8 months 12 days
Weighted Average Remaining Contractual Term, Options exercisable at end of period	7 years 6 months