Shareholders’ Equity (Narrative) (Details)	1 Months Ended							12 Months Ended
	Mar. 31, 2019 shares	Jul. 31, 2018 USD ($) shares	Mar. 31, 2018 USD ($) shares	Jan. 31, 2017 shares	Jan. 31, 2016 shares	Dec. 31, 2014 party shares	Sep. 30, 2013	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Jan. 31, 2019 shares	Dec. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Shares underlying stock options and restricted stock awards (in shares)								2,126,023
Weighted-average grant date fair values of stock options granted (in dollars per share) | $ / shares								$ 4.99	$ 20.52
Unamortized share-based compensation expense | $								$ 18,400,000
Recognized weighted average period								2 years 3 months 3 days
Stock options exercised (in shares)								5,211
Intrinsic value of stock options exercised | $								$ 100,000	$ 1,427,976.00
Total fair value of equity awards vested | $								25,900,000	38,000,000
Warrants granted to purchase common stock (in shares)						51,000
Warrants issued, number of third party recipients (party) | party						2
Share-based compensation expense | $								$ 24,000	35,000
Grant One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant vesting period						4 years
Chief Commercial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Shares underlying stock options and restricted stock awards (in shares)	80,000
Chief Commercial Officer [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	25.00%
Period of share-based payment awards	3 years
One-year Anniversary Date of Grant [Member] | Grant One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant vesting rights percentage						25.00%
One-year Anniversary Date of Grant [Member] | Grant Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant vesting rights percentage				100.00%	100.00%	100.00%
2013 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity plan, term							10 years
Period of share-based payment awards							4 years
Shares of common stock authorized for issuance (in shares)											9,600,000
Shares available for grant (in shares)								3,769,824
2013 Equity Plan [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards							1 year
2013 Equity Plan [Member] | One-year Anniversary Date of Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage							25.00%
2018 Employee Stock Purchase Plan [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)		750,000						568,728
Maximum number of shares per employee | $		$ 25,000
Percent of employee's annual cash compensation		85.00%
Share-based compensation expense | $								$ 100,000	$ 200,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised (in shares)								5,000	150,000
Shares of common stock issued (in shares)			43,056					782,000	3,910,000
Warrants exercised during period (in shares)			83,013
Warrants outstanding (in shares)								10,000
Series C-1 Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized (in shares)								11,000	11,000
Preferred stock, par value (usd per share) | $ / shares								$ 0.0001	$ 0.0001
Preferred stock, shares issued (in shares)								3,906	3,906
Preferred stock, shares outstanding (in shares)								3,906	3,906
Shares reserved for future issuance (in shares)								6,735,378	6,735,378
Liquidation preference per share (in dollars per share) | $ / shares								$ 1,000
Liquidation preference | $								$ 3,906,000	$ 3,906,000
Series F Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized (in shares)								10,000	10,000
Preferred stock, par value (usd per share) | $ / shares								$ 0.0001	$ 0.0001
Preferred stock, shares issued (in shares)								0	2,737
Preferred stock, shares outstanding (in shares)								0	2,737
Shares reserved for future issuance (in shares)									782,032
Liquidation preference per share (in dollars per share) | $ / shares									$ 1,000
Liquidation preference | $								$ 0	$ 2,737,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued upon conversion, per share (in shares)										782,031
Warrant granted to purchase common stock (in shares)				25,013	17,000
Underwriting Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock to be issued and sold in underwriting agreement (in shares)			3,910,000
Price per share of shares sold (usd per share) | $ / shares								$ 29.50
Proceeds from the underwriting agreement, including additional shares sold, gross | $			$ 115,300,000
Proceeds from the underwriting agreement, including additional shares sold, net of cost | $			109,800,000
Issuance costs | $			$ 5,500,000