Organization and Nature of Business - IPO, Stock Split, Liquidity (Details) $ / shares in Units, $ in Thousands				9 Months Ended
	Jun. 02, 2016 USD ($) $ / shares shares	Oct. 13, 2015 USD ($) $ / shares shares	Sep. 24, 2015	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Initial public offering
Issuance of common stock in connection with private placement, net of offering costs				$ 18,547
Common stock shares issued upon conversion of convertible preferred stock | shares		11,677,076
Offering costs					$ 1,507
Reverse stock split			0.2899
Cash, cash equivalents and marketable securities				84,042
Accumulated deficit				$ 79,437		$ 42,833
IPO
Initial public offering
Number of shares issued | shares		5,000,000
Issuance price (in dollars per share) | $ / shares		$ 11.00
Issuance of common stock in connection with private placement, net of offering costs		$ 55,000
Offering costs		2,272
Offering proceeds, net of discounts, commissions and expenses		$ 56,550
Exercise of over-allotment option
Initial public offering
Number of shares issued | shares		750,000
Issuance price (in dollars per share) | $ / shares		$ 11.00
Issuance of common stock in connection with private placement, net of offering costs		$ 8,250
Offering costs	$ 1,300	$ 4,428
Private Placement [Member]
Initial public offering
Number of shares issued | shares	1,081,082
Issuance price (in dollars per share) | $ / shares	$ 18.50
Issuance of common stock in connection with private placement, net of offering costs	$ 20,000
Offering costs	153
Offering proceeds, net of discounts, commissions and expenses	$ 18,547