Subsequent Events (Details) - $ / shares					1 Months Ended					12 Months Ended
		Jul. 24, 2019	Apr. 30, 2019	Feb. 05, 2019	Jun. 30, 2019	May 31, 2019	Mar. 31, 2019	Feb. 28, 2019	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Options [Member]
Number of Stock Options [Abstract]
Options, exercised (in shares)										0	0
Options, Exercise price (in dollars per share)										$ 3.78
Expiration Date, February 2019 [Member]
Warrants and Rights [Abstract]
Expiration Date	[1]									Feb. 05, 2019
Exercise price (in dollars per share)	[1]									$ 3.75
Expiration Date, April 2019 [Member]
Warrants and Rights [Abstract]
Expiration Date	[1]									Apr. 30, 2019
Exercise price (in dollars per share)	[1]									$ 3.75
Expiration Date, July 2019 [Member]
Warrants and Rights [Abstract]
Expiration Date										Jul. 24, 2019
Expiration Date, July 2019 [Member] | Minimum [Member]
Warrants and Rights [Abstract]
Exercise price (in dollars per share)										$ 3.75
Expiration Date, July 2019 [Member] | Maximum [Member]
Warrants and Rights [Abstract]
Exercise price (in dollars per share)										$ 12.25
Series C Convertible Preferred Stock [Member]
Subsequent Events [Abstract]
Number of common shares issued on conversion of preferred stock (in shares)										9,744,916	1,598,346
Subsequent Event [Member] | Stock Options [Member]
Number of Stock Options [Abstract]
Options, exercised (in shares)						(15,000)	(30,000)	(30,000)
Options, Exercise price (in dollars per share)						$ 1.29
Common stock shares issued on exercise of options (in shares)						7,586	19,228	9,596
Subsequent Event [Member] | Stock Options [Member] | Minimum [Member]
Number of Stock Options [Abstract]
Options, Exercise price (in dollars per share)							$ 1.29	$ 1.29
Subsequent Event [Member] | Stock Options [Member] | Maximum [Member]
Number of Stock Options [Abstract]
Options, Exercise price (in dollars per share)							$ 2.75	$ 2.75
Subsequent Event [Member] | Expiration Date, February 2019 [Member]
Warrants and Rights [Abstract]
Expiration Date				Feb. 05, 2019
Warrants expired (in shares)				(265,947)
Exercise price (in dollars per share)				$ 3.75
Subsequent Event [Member] | Expiration Date, April 2019 [Member]
Warrants and Rights [Abstract]
Expiration Date			Apr. 30, 2019
Warrants expired (in shares)			(137,143)
Exercise price (in dollars per share)			$ 3.75
Subsequent Event [Member] | Expiration Date, July 2019 [Member]
Warrants and Rights [Abstract]
Expiration Date		Jul. 24, 2019
Warrants expired (in shares)		(1,239,769)
Subsequent Event [Member] | Expiration Date, July 2019 [Member] | Minimum [Member]
Warrants and Rights [Abstract]
Exercise price (in dollars per share)		$ 3.75
Subsequent Event [Member] | Expiration Date, July 2019 [Member] | Maximum [Member]
Warrants and Rights [Abstract]
Exercise price (in dollars per share)		$ 12.25
Subsequent Event [Member] | Series C Convertible Preferred Stock [Member]
Subsequent Events [Abstract]
Number of common shares issued on conversion of preferred stock (in shares)					1,775,093				1,148,698

[1] These warrants are classified as liabilities (See Note 13, Warrants).