Stockholders' Equity - Preferred Stock and Warrants (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	9 Months Ended		1 Months Ended
	May 31, 2014 Common stock	Sep. 30, 2014 Common stock	Nov. 30, 2013 Vulcan Common Stock Purchase Warrants	May 31, 2014 Vulcan Series A preferred stock	Nov. 30, 2013 Vulcan Series A preferred stock
Stockholders' Equity
Shares sold		8,941,250			2,857,143
Number of shares that may be purchased under warrant			666,666
Exercise price of warrants (in dollars per share)			$ 15.00
Private placement price per share					$ 10.50
Aggregate purchase price for preferred stock and warrants					$ 30.0
Shares of common stock issued for conversion of Series A preferred	2,857,143	2,857,143
Initial conversion rate				1