Shareholders' Equity - Summary of Shares of Common Stock Reserved for Future Issuance under Plans (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Common Stock Number Of Shares Par Value And Other Disclosures [Abstract]
Stock options outstanding	1,846,768	1,778,697	1,553,360
Restricted stock units outstanding	119,606	104,463
Stock options available for future grant	689,160	1,020,477
Common stock reserved for future issuance	2,655,534	2,903,637