Stock-Based Compensation - Schedule of Stock Options Outstanding (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 1.31
Range of Exercise Prices, Upper Range Limit	$ 68.90
Options Exercisable, Number Exercisable	1,308,835
Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 0.01
Range of Exercise Prices, Upper Range Limit	$ 3.00
Options Outstanding, Number Outstanding	1,125,000
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	9 years 11 months 12 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 1.40
Options Exercisable, Number Exercisable	0
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 0
Range Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 3.01
Range of Exercise Prices, Upper Range Limit	$ 10.00
Options Outstanding, Number Outstanding	147,553
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	8 years 11 months 23 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 6.95
Options Exercisable, Number Exercisable	70,443
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 7.51
Range Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 10.01
Range of Exercise Prices, Upper Range Limit	$ 70.00
Options Outstanding, Number Outstanding	36,282
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	7 years 4 months 28 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 27.89
Options Exercisable, Number Exercisable	30,933
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 26.97
Net Range [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range Limit	$ 0.01
Range of Exercise Prices, Upper Range Limit	$ 70.00
Options Outstanding, Number Outstanding	1,308,835
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	9 years 9 months 7 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 2.76
Options Exercisable, Number Exercisable	101,376
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 13.45