Description of Business and Summary of Significant Accounting Policies - Summary of Fair Value Maturities for Financial Asset (Detail) $ in Thousands |
Dec. 31, 2017
USD ($)
|
---|---|
Fair Value Disclosures [Abstract] | |
Cash equivalents and marketable securities, Maturities by Period, Total | $ 66,676 |
Cash equivalents and marketable securities, Maturities by Period, Less than 1 year | 66,676 |
Cash equivalents and marketable securities, Maturities by Period, 1-5 years | 0 |
Cash equivalents and marketable securities, Maturities by Period, 5-10 years | 0 |
Cash equivalents and marketable securities, Maturities by Period, More than 10 years | $ 0 |