Stockholders' (Deficit) Equity - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common
Options Outstanding, Ending Balance (in shares)	61,013
Weighted Average Exercise Price
Ending Balance, Weighted Average Exercise Price (in dollars per share)	$ 2.19
Employee Stock Option
Common
Options Outstanding, Beginning Balance (in shares)	187,707	1,394,869	1,030,521
Granted (in shares)			850,000
Exercised (in shares)	(44,114)	(226,011)	(171,718)
Canceled (in shares)	(57,580)	(533,484)	(313,934)
Forfeited (in shares)	(25,000)	(447,667)
Options Outstanding, Ending Balance (in shares)	61,013	187,707	1,394,869
Weighted Average Exercise Price
Beginning Balance, Weighted Average Exercise Price (in dollars per share)	$ 5.78	$ 3.40	$ 5.29
Granted, Weighted Average Exercise Price (in dollars per share)			2.68
Exercised, Weighted Average Exercise Price (in dollars per share)	2.50	1.41	1.68
Canceled, Weighted Average Exercise Price (in dollars per share)	13.32	3.99	8.61
Forfeited, Weighted Average Exercise Price (in dollars per share)	2.95	2.71
Ending Balance, Weighted Average Exercise Price (in dollars per share)	$ 2.19	$ 5.78	$ 3.40