Investments in Marketable Securities - Amortized Cost and Fair Value of Investments in Available for Sale Securities (Detail) - USD ($) $ in Thousands |
Sep. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Investments, Debt and Equity Securities [Abstract] | ||
| Available for sale securities continuous unrealized loss position for less than 12 months, unrealized loss | $ (28) | $ (576) |
| Available for sale securities continuous unrealized loss position for 12 months or longer, unrealized loss | (4) | (383) |
| Available for sale securities continuous unrealized loss position for less than 12 months, fair value | 11,931 | 127,326 |
| Available for sale securities continuous unrealized loss position for 12 months or longer, fair value | $ 1,071 | $ 30,609 |
| X | ||||||||||
- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. No definition available.
|
| X | ||||||||||
- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. No definition available.
|
| X | ||||||||||
- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. No definition available.
|
| X | ||||||||||
- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. No definition available.
|
| X | ||||||||||
- References No definition available.
|