Equity Incentive Plans - Summary of Option Activity under Company's Share-Based Compensation Plans (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at January 1, 2015, Number of Shares | shares	1,978,273
Options granted, Number of Shares | shares	1,544,300
Options exercised, Number of Shares | shares	0
Options forfeited, Number of Shares | shares	0
Options canceled, Number of Shares | shares	(1,196,172)
Outstanding at December 31, 2015, Number of Shares | shares	2,326,401
Outstanding at January 1, 2015, Weighted Average Exercise Price | $ / shares	$ 7.10
Options granted, Weighted Average Exercise Price | $ / shares	1.19
Options exercised, Weighted Average Exercise Price | $ / shares	0
Options forfeited, Weighted Average Exercise Price | $ / shares	0
Options canceled, Weighted Average Exercise Price | $ / shares	5.04
Outstanding at September 30, 2015, Weighted Average Exercise Price | $ / shares	$ 4.23