Fair Value Measurements - Warrants and other (Details) - USD ($)	1 Months Ended			3 Months Ended	9 Months Ended		12 Months Ended
	Feb. 29, 2016	Sep. 30, 2015	Feb. 28, 2015	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value Measurements, Valuation
Change in fair value of stock warrant liability				$ 31,000	$ 43,000	$ (1,130,000)
Amount of transfers of assets and liabilities measured on a recurring basis between Levels 1, 2 and 3 of the fair value hierarchy					0		$ 0
Common Stock Warrants | Amended Agreement
Fair Value Measurements, Valuation
Shares that may be purchased under warrant (in shares)			11,298				5,649
Exercise price of warrants (in dollars per share)			$ 8.85
Stock warrant liabilities, fair value			$ 53,000				$ 100,000
Warrants exercised (in shares)	5,649	5,649
Change in fair value of stock warrant liability				$ 31,000	$ 43,000	$ (1,100,000)
Fair Value Assumptions
Risk free interest rate (as a percent)			1.90%				1.90%
Dividend yield (as a percent)			0.00%				0.00%
Expected volatility rate (as a percent)			70.00%				54.80%
Expected life			7 years				6 years 2 months 12 days