Shareholders’ Equity (Narrative) (Details) $ / shares in Units, $ in Thousands			1 Months Ended							3 Months Ended		9 Months Ended			12 Months Ended
	Jan. 25, 2014 USD ($) shares	Jan. 14, 2014	Sep. 30, 2015 USD ($) $ / shares shares	Aug. 31, 2015 USD ($) shares	Apr. 30, 2015 shares	Feb. 28, 2015 shares	Dec. 31, 2014 party $ / shares shares	Jul. 31, 2014 USD ($) $ / shares shares	Sep. 30, 2013	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 USD ($) $ / shares	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 USD ($) $ / shares	Sep. 30, 2013 shares	Dec. 31, 2014 $ / shares shares	Jul. 31, 2015 shares	Aug. 31, 2014 shares	Jan. 02, 2014 shares	Dec. 31, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reverse stock split ratio		0.02
Common stock, shares authorized			100,000,000				100,000,000	12,000,000,000		100,000,000		100,000,000			100,000,000		100,000,000
Preferred stock, shares authorized			8,000,000							8,000,000		8,000,000
Preferred stock, par value (usd per share) | $ / shares			$ 0.0001							$ 0.0001		$ 0.0001
Weighted-average grant date fair values of stock options granted | $ / shares										$ 21.49	$ 8.38	$ 21.13	$ 9.49
Unamortized share-based compensation expense | $			$ 19,856							$ 19,856		$ 19,856
Recognized weighted average period												2 years 11 months 25 days
Stock options exercised										35,035		42,535			0
Intrinsic value of stock options exercised | $										$ 641		$ 752
Warrants granted to purchase common stock							51,000
Warrants issued, number of third party recipients | party							2
Third party share-based compensation expense | $										197		613
Share-based compensation expense | $										3,061	$ 1,743	10,343	$ 6,595
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $										891	245	3,101	794
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $										$ 2,170	1,498	$ 7,242	5,801
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued				4,000
Number of shares of unvested stock awards			1,090,593				1,279,007			1,090,593		1,090,593			1,279,007				1,746,853
Stock issued during period, value | $				$ 92
Restricted Stock [Member] | Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized weighted average period												4 months
Share-based compensation expense | $										$ 240	147	$ 1,452	652
Unamortized share-based compensation expense | $			$ 178							178		$ 178
Restricted Stock [Member] | General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized weighted average period												17 months
Share-based compensation expense | $										545	$ 1,212	$ 3,719	$ 5,226
Unamortized share-based compensation expense | $			$ 3,117							$ 3,117		$ 3,117
Grant One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant vesting period							4 years
Consultant [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued	2,976
Stock issued during period, value | $	$ 25
Chief Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of unvested stock awards																1,042,680
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%
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
Automatic annual increase based on outstanding shares of Common Stock as of the last day of the previous year end, percent									10.00%
Shares available for grant			1,613,525							1,613,525		1,613,525						440,441
Shares of common stock authorized for issuance			3,100,000							3,100,000		3,100,000					1,100,000
Shares of common stock for future issuance			3,047,710							3,047,710		3,047,710
2013 Equity Plan [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards						3 years
Stock options granted						60,000
Share-based compensation expense | $										$ 0		$ 362
2013 Equity Plan [Member] | Consultant [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted				40,000
Share-based compensation expense | $										$ 38		$ 38
2013 Equity Plan [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of share-based payment awards									3 years
2013 Equity Plan [Member] | Chief Financial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted					60,000
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%
2013 Equity Plan [Member] | One-year Anniversary Date of Grant [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage									33.00%
2013 Equity Plan [Member] | One-year Anniversary Date of Grant [Member] | Chief Financial Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					25.00%
2013 Equity Plan [Member] | Upon Grant [Member] | Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage						25.00%
Common Stock [Member] | Director [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued														79,622
Common Stock [Member] | Chief Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued														1,327,048
Common Stock [Member] | Employees [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued														336,185
Series C-1 Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized			11,000				11,000			11,000		11,000			11,000
Preferred stock, par value (usd per share) | $ / shares			$ 0.0001				$ 0.0001			$ 0.0001		$ 0.0001			$ 0.0001
Shares issued upon conversion, per share			1,724							1,724		1,724
Preferred stock, shares issued			3,906				3,917			3,906		3,906			3,917
Shares reserved for future issuance			6,735,378							6,735,378		6,735,378
Liquidation preference per share | $ / shares			$ 1,000							$ 1,000		$ 1,000
Liquidation preference | $			$ 3,906							$ 3,906		$ 3,906
Series C-1 Convertible Preferred Stock [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued												19,134			5,341,670
Series F Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized			10,000				10,000			10,000		10,000			10,000
Preferred stock, par value (usd per share) | $ / shares			$ 0.0001				$ 0.0001			$ 0.0001		$ 0.0001			$ 0.0001
Shares issued upon conversion, per share			286							286		286
Preferred stock, shares issued			2,737				2,798			2,737		2,737			2,798
Shares reserved for future issuance			782,032							782,032		782,032
Liquidation preference | $			$ 2,737							$ 2,737		$ 2,737
Series F Preferred Stock [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued												17,360			129,105
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			2,932,500					5,395,000
Proceeds from the underwriting agreement, including additional shares sold, gross | $			$ 111,400					$ 56,600
Proceeds from the underwriting agreement, including additional shares sold, net of cost | $			104,600					53,100
Issuance costs | $			$ 6,800					$ 3,500
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price per share of shares sold (usd per share) | $ / shares			$ 38					$ 10.50		$ 38		$ 38