Long-Term Investments - Additional Information (Detail) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Investments Schedule [Abstract] | |||
| Auction rate securities held, at par value | $ 2,500,000 | ||
| Maturity of long-term investment | 2038 | ||
| Assumed interest rate | 1.64% | ||
| Estimated redemption period | 5 years | ||
| Fair value input discount rate | 1.00% | ||
| Recognized cumulative losses | $ 500,000 | ||
| Unrealized (losses) gains on auction rate securities | (6,000) | $ 48,000 | $ (9,000) |
| Cumulative unrealized gains | 200,000 | ||
| Carrying value of auction rate security | 2,046,000 | $ 2,052,000 | |
| Recognized cumulative losses realized | $ 0 | ||