Cash and Cash Equivalents and Marketable Securities - Summary of Available for Sale Securities (Detail) $ in Thousands |
Sep. 30, 2016
USD ($)
|
|---|---|
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost | $ 67,840 |
| Unrealized Gains | 17 |
| Unrealized Losses | (3) |
| Fair Value | 67,854 |
| U.S. treasury securities [Member] | |
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost | 55,092 |
| Unrealized Gains | 14 |
| Unrealized Losses | (3) |
| Fair Value | 55,103 |
| Government agencies [Member] | |
| Schedule Of Available For Sale Securities [Line Items] | |
| Amortized Cost | 12,748 |
| Unrealized Gains | 3 |
| Fair Value | $ 12,751 |