Cash and Cash Equivalents and Marketable Securities - Additional Information (Detail) |
3 Months Ended | 9 Months Ended |
|---|---|---|
|
Sep. 30, 2016
USD ($)
|
Sep. 30, 2016
USD ($)
|
|
| Cash And Cash Equivalents [Abstract] | ||
| Realized gains or losses on marketable securities | $ 0 | $ 0 |
| Other-than-temporary impairments of investments | 0 | 0 |
| Available for sale securities have remaining maturities greater than one year | $ 0 | $ 0 |