Reconciliation of Change in Value of Company's Warrants Liability (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Class of Warrant or Right [Line Items]
Beginning balance	$ 9,213	$ 91,077	$ 9,006	$ 65,193
Increase in value of warrants	3,784	1,945	7,035	28,851
Ending balance	9,826	79,116	9,826	79,116
Warrant [Member]
Class of Warrant or Right [Line Items]
Reclassification to stockholders' equity upon exercise of warrants	$ (3,171)	$ (13,906)	$ (6,215)	$ (14,928)