Stockholders' Equity - Preferred Stock and Warrants (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	6 Months Ended	1 Months Ended		1 Months Ended
	May 31, 2014 Common stock	Jun. 30, 2014 Common stock	Nov. 30, 2013 Vulcan	Nov. 30, 2013 Vulcan Common Stock Purchase Warrants	May 31, 2014 Vulcan Convertible preferred stock	Nov. 30, 2013 Vulcan Convertible preferred stock
Class of Stock [Line Items]
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
Initial conversion rate					1
Shares of common stock issued for conversion of Series A preferred	2,857,143	2,857,143