Stock Based Awards - Stock Options Outstanding and Exercisable under Stock Option Plans (Detail)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number	3,240,969
Options Exercisable and Vested, Outstanding Number	1,360,952
$1.27 - $1.61 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit | $ / shares	$ 1.27
Range of Exercise Price, Upper Limit | $ / shares	$ 1.61
Options Outstanding, Number	678,905
Options Outstanding, Weighted Average Remaining Contractual Life (Years)	6 years 7 months 6 days
Options Exercisable and Vested, Outstanding Number	533,010
Options Exercisable and Vested, Weighted Average Remaining Contractual Life (Years)	6 years 7 months 6 days
$2.53 - $8.17 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit | $ / shares	$ 2.53
Range of Exercise Price, Upper Limit | $ / shares	$ 8.17
Options Outstanding, Number	1,074,463
Options Outstanding, Weighted Average Remaining Contractual Life (Years)	7 years 9 months 18 days
Options Exercisable and Vested, Outstanding Number	535,847
Options Exercisable and Vested, Weighted Average Remaining Contractual Life (Years)	7 years 9 months 18 days
$10.59 - $18.67 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit | $ / shares	$ 10.59
Range of Exercise Price, Upper Limit | $ / shares	$ 18.67
Options Outstanding, Number	656,850
Options Outstanding, Weighted Average Remaining Contractual Life (Years)	9 years 4 months 24 days
Options Exercisable and Vested, Outstanding Number	10,969
Options Exercisable and Vested, Weighted Average Remaining Contractual Life (Years)	9 years 4 months 24 days
$18.72 - $31.96 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit | $ / shares	$ 18.72
Range of Exercise Price, Upper Limit | $ / shares	$ 31.96
Options Outstanding, Number	820,751
Options Outstanding, Weighted Average Remaining Contractual Life (Years)	8 years 6 months
Options Exercisable and Vested, Outstanding Number	277,376
Options Exercisable and Vested, Weighted Average Remaining Contractual Life (Years)	8 years 6 months
$34.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, Lower Limit | $ / shares	$ 34.00
Range of Exercise Price, Upper Limit | $ / shares	$ 34.00
Options Outstanding, Number	10,000
Options Outstanding, Weighted Average Remaining Contractual Life (Years)	8 years 6 months
Options Exercisable and Vested, Outstanding Number	3,750
Options Exercisable and Vested, Weighted Average Remaining Contractual Life (Years)	9 years 6 months