Reconciliation of Change in Value of Company's Warrants Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		404 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Class of Warrant or Right [Line Items]
Beginning balance	$ 9,006	$ 65,193
Increase in value of warrants	3,251	26,906	92,246
Ending balance	9,213	91,077	9,213
Warrant
Class of Warrant or Right [Line Items]
Reclassification to stockholders' equity upon exercise of warrants	$ (3,044)	$ (1,022)