Information Pertaining to Convertible Notes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		106 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Convertible Debt [Line Items]
Balance - December 31, 2013	$ 14,501
Amortization of debt discount	571
(Gain) loss from change in fair value of embedded derivative	(1,264)	1,330	(21,378)
Balance - March 31, 2014	13,808		13,808
Embedded Derivatives
Convertible Debt [Line Items]
Balance - December 31, 2013	3,470
(Gain) loss from change in fair value of embedded derivative	(1,264)
Balance - March 31, 2014	2,206		2,206
Convertible debt
Convertible Debt [Line Items]
Balance - December 31, 2013	26,900
Amortization of debt discount
(Gain) loss from change in fair value of embedded derivative
Balance - March 31, 2014	26,900		26,900
Debt Discount
Convertible Debt [Line Items]
Balance - December 31, 2013	(15,869)
Amortization of debt discount	571
Balance - March 31, 2014	$ (15,298)		$ (15,298)