Summary of Preferred Stock (Detail)	Jun. 30, 2012	Dec. 31, 2011
Class of Stock [Line Items]
Preferred stock, shares issued	373,355	373,355	[1]
Preferred stock, shares outstanding	373,355	373,355	[1]
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued	47,250	47,250
Preferred stock, shares outstanding	47,250	47,250
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued	93,750	93,750
Preferred stock, shares outstanding	93,750	93,750
Series C Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued	38,333	38,333
Preferred stock, shares outstanding	38,333	38,333
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued	175,000	175,000
Preferred stock, shares outstanding	175,000	175,000
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued	19,022	19,022
Preferred stock, shares outstanding	19,022	19,022

[1] Derived from audited information