Common Stock and Stock Warrants - Warrants (Details) - $ / shares	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Class of Warrant or Right [Line Items]
Number of warrants outstanding	250,539	250,646
Series B [Member]
Class of Warrant or Right [Line Items]
Number of warrants expired in period	107
Series C [Member]
Class of Warrant or Right [Line Items]
Number of warrants outstanding	9,919
Exercise price (usd per share)	$ 147.91
Series D [Member]
Class of Warrant or Right [Line Items]
Number of warrants outstanding	240,620
Exercise price (usd per share)	$ 92.99