Available-for-Sale Securities - Summary of Amortized Cost and Fair Value of Available-for-Sale Securities by Contractual Maturity (Detail) $ in Thousands |
Sep. 30, 2016
USD ($)
|
|---|---|
| Available For Sale Securities Debt Maturities [Abstract] | |
| Amortized Cost, Due in one year or less | $ 75,024 |
| Amortized Cost | 75,024 |
| Fair Value, Due in one year or less | 75,054 |
| Aggregate Fair Value | $ 75,054 |