Summary of Warrant Outstanding and Exercisable (Detail) (Warrants, USD $)	12 Months Ended
	Dec. 31, 2013
$1.21 to $ 4.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Minimum, warrant	$ 1.21
Exercise Price Maximum, warrant	$ 4.99
Weighted Average Remaining Contractual Life (years), warrant	2 years 9 months 15 days
Number of warrants Outstanding	2,409,033
Number of warrants Exercisable	2,409,033
$5.00 to $10.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Minimum, warrant	$ 5.00
Exercise Price Maximum, warrant	$ 10.44
Weighted Average Remaining Contractual Life (years), warrant	4 months 24 days
Number of warrants Outstanding	660,080
Number of warrants Exercisable	660,080
$1.21 to $10.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Minimum, warrant	$ 1.21
Exercise Price Maximum, warrant	$ 10.44
Weighted Average Remaining Contractual Life (years), warrant	3 years 2 months 9 days
Number of warrants Outstanding	3,069,113
Number of warrants Exercisable	3,069,113