Common Stock, warrants, stock-based compensation, stock options, restricted stock and restricted stock units- Common stock reserved (Details) - shares	Dec. 31, 2019	Dec. 31, 2018
Warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Shares reserved for future awards under compensation plan	882,715	2,433,999
Common stock reserved	3,809,706	5,348,442
Outstanding warrants
Warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Common stock reserved	10,000	76,041
Common stock options and unvested restricted common stock
Warrants, stock-based compensation, stock options, restricted stock and restricted stock units
Common stock reserved	2,916,991	2,838,402