Preferred Stock and Warrants (Summary of Preferred Stock) (Parenthetical) (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Convertible preferred stock, cumulative dividend rate		10.00%
Series B Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock, cumulative dividend rate	10.00%	10.00%
Series C Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock, cumulative dividend rate	10.00%	10.00%
Series D Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock, cumulative dividend rate	10.00%	10.00%
Series E Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock, cumulative dividend rate	10.00%	10.00%