Business and Organization (Details) - USD ($)			3 Months Ended		9 Months Ended
	Nov. 06, 2017	Mar. 10, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Net loss			$ 115,000	$ 2,299,000	$ 19,140,000	$ 11,798,000
Cash used in operating activities					12,879,000	25,596,000
Cash and cash equivalents			11,911,000	$ 21,283,000	11,911,000	$ 21,283,000	$ 17,515,000	$ 29,268,000
Working capital			$ 8,700,000		$ 8,700,000
Reverse stock split		33.33%
Common stock, par value (in dollars per share)			$ 0.001		$ 0.001		$ 0.001
Minimum bid price requirement (in dollars per share)					$ 1.00
Subsequent event
Subsequent Event [Line Items]
Value of company securities offered in registration statement	$ 24,150,000
Registration Statement | Subsequent event
Subsequent Event [Line Items]
Value of common stock offered in registration statement	23,000,000
Value of warrants offered in registration statement	$ 1,150,000