Reconciliation of Change in Value of Company's Warrants Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		395 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Class of Warrant or Right [Line Items]
Beginning balance	$ 91,077		$ 65,193
Increase in value of warrants	(1,945)	13,488	(28,851)	2,562	(95,819)
Ending balance	79,116		79,116		79,116
Warrant
Class of Warrant or Right [Line Items]
Reclassification to stockholders' equity upon exercise of warrants	$ (13,906)		$ (14,928)