Annual report pursuant to Section 13 and 15(d)

Stock Plans and Stock-Based Compensation - Summary of Stock Options Outstanding (Detail)

Stock Plans and Stock-Based Compensation - Summary of Stock Options Outstanding (Detail)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Outstanding Number of Shares	1,804,083
Weighted-Average Remaining Contractual Term (Years)	8 years 2 months 27 days
Options Exercisable Number of Shares	783,856
$1.98 - $4.77 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Outstanding Number of Shares	108,483
Weighted-Average Remaining Contractual Term (Years)	8 years 11 months 12 days
Options Exercisable Number of Shares	65,800
$1.98 - $4.77 [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 1.98
$1.98 - $4.77 [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	4.77
$5.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 5.00
Option Outstanding Number of Shares	858,442
Weighted-Average Remaining Contractual Term (Years)	7 years 6 months 26 days
Options Exercisable Number of Shares	617,070
$5.23 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 5.23
Option Outstanding Number of Shares	10,000
Weighted-Average Remaining Contractual Term (Years)	8 years 7 months 24 days
Options Exercisable Number of Shares	3,333
$5.90 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 5.90
Option Outstanding Number of Shares	18,000
Weighted-Average Remaining Contractual Term (Years)	9 years 3 months 15 days
Options Exercisable Number of Shares	18,000
$6.85 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 6.85
Option Outstanding Number of Shares	12,000
Weighted-Average Remaining Contractual Term (Years)	8 years 8 months 23 days
Options Exercisable Number of Shares	4,500
$7.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 7.00
Option Outstanding Number of Shares	77,000
Weighted-Average Remaining Contractual Term (Years)	8 years 3 months 11 days
Options Exercisable Number of Shares	32,083
$7.99 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 7.99
Option Outstanding Number of Shares	6,500
Weighted-Average Remaining Contractual Term (Years)	8 years 4 months 10 days
Options Exercisable Number of Shares	2,594
$10.00 - $10.49 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Outstanding Number of Shares	710,203
Weighted-Average Remaining Contractual Term (Years)	8 years 11 months 5 days
Options Exercisable Number of Shares	37,021
$10.00 - $10.49 [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 10.00
$10.00 - $10.49 [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	10.49
$238.50 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price \| $ / shares	$ 238.50
Option Outstanding Number of Shares	3,455
Weighted-Average Remaining Contractual Term (Years)	8 months 23 days
Options Exercisable Number of Shares	3,455