Stockholders' Equity - Employee Stock Purchase Plan and Stock-Based Compensation - Additional Information (Detail) - USD ($)		6 Months Ended
	May 03, 2017	Jun. 30, 2017	Jun. 30, 2016	May 02, 2017
Sale Of Stock [Line Items]
Payroll withholdings from employees		$ 80,000	$ 99,000
Issuance of common stock under employee stock purchase plan		50,244	34,067
Unrecognized compensation costs		$ 2,200,000
Weighted average period		11 months 5 days
Amended and Restated ESPP [Member]
Sale Of Stock [Line Items]
Increase in number of shares of common stock reserved under the plan	100,000
Number of shares increased annually to common stock shares reserved for issuance	100,000			30,000
Aggregate number of shares of common stock reserved under the plan	1,250,000
Award plan expiration year	2027