Preferred Stock, Common Stock and Stockholders' Equity - Stock Options - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Feb. 29, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) Option $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Jan. 01, 2016 shares	Aug. 31, 2013 shares	May. 31, 2007 shares
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance		1,276,765	1,043,457
Options available for future grant		78,854	188,370
Number of stock options granted		354,000
Intrinsic value, common stock price | $ / shares		$ 3.30	$ 5.90
Stock options vested		270,998
Number of stock options unvested		507,421	424,419
Total intrinsic value of stock options exercised | $			$ 33,810
Intrinsic value of stock option exercised, common stock price | $ / shares			$ 6.73
Weighted Average Grant Date Fair Value Per Share, Granted | $ / shares		$ 4.03	$ 4.76
Number of stock options exchanged, outstanding		1,037,500	683,500
Replacement stock options exercise price | $ / shares		$ 7.19	$ 7.67
Unrecognized compensation costs | $		$ 2,300,000
Weighted average period		1 year 1 month 17 days
Subsequent Event [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock options exchanged, outstanding	703,500
Options Granted [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, weighted average term		10 years
Number of stock options granted		354,000	64,000
Options Granted [Member] | Minimum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting period		1 year
Options Granted [Member] | Maximum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting period		4 years
2007 Equity Incentive Plan [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance		0				450,000
Issuance of common stock upon exercise of stock option, Shares		332,000
Stock options vested		287,000	287,000
Number of stock options unvested		45,000
Number of options exercised | Option		0
2013 Equity Incentive Award Plan [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance					510,000
Additional common stock reserved for issuance		488,354
Shares of common stock available for issuance description		In addition, the number of shares of common stock available for issuance under the 2013 Plan will be annually increased on the first day of each fiscal year during the term of the 2013 Plan, beginning with the 2014 fiscal year, by an amount equal to the least of: (i) 300,000 shares; (ii) four percent of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the Company’s board of directors may determine.
Options available for future grant		78,854
2013 Equity Incentive Award Plan [Member] | Subsequent Event [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance				288,071
Options available for future grant				366,925
2013 Equity Incentive Award Plan [Member] | Annual Increase in Shares [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance		300,000
Reserve percentage for issuance of shares		4.00%
One-Time Option Exchange Program [Member] | Subsequent Event [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant	175,876
Options granted, vesting period	3 years
Number of stock options exchanged, outstanding	527,624
Number of stock options exchange percentage	75.00%
Replacement stock options exercise price | $ / shares	$ 3.04
Incremental compensation expense during period under option exchange | $	$ 4,700
Unrecognized compensation costs | $	$ 141,000
Weighted average period	3 years