Reconciliation of Change in Value of Company's Warrants Liability (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Class of Warrant or Right [Line Items]
Beginning balance	$ 9,826	$ 79,116	$ 9,006	$ 65,193
(Decrease) increase in value of warrants	(4,256)	17,160	2,779	46,011
Ending balance		35,994		35,994
Warrant [Member]
Class of Warrant or Right [Line Items]
Reclassification to stockholders' equity upon exercise of warrants	$ (5,570)	$ (60,282)	$ (11,785)	$ (75,210)