Warrants (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Preferred stock warrants
Shares Exercisable	297,988	297,988
Warrants 2013
Preferred stock warrants
Exercise Price	$ 7.50
Shares Exercisable	82,816	82,816
Warrants 2014
Preferred stock warrants
Exercise Price	$ 7.50
Shares Exercisable	16,000	16,000
Warrants 2016
Preferred stock warrants
Exercise Price	$ 8.27
Shares Exercisable	14,512	14,512
Warrants 2018
Preferred stock warrants
Exercise Price	$ 12.18
Shares Exercisable	184,660	184,660
Shares Exercisable upon condition	86,175	86,175