|
Fair Value Measurements of Financial Assets and Liabilities - Additional Information (Detail) (USD $)
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9 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
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Sep. 30, 2014
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Sep. 30, 2013
|
Sep. 30, 2014
Short-term Investments
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Dec. 31, 2013
Short-term Investments
|
|
| Impairment charge | $ 66,000 | $ 155,000 | $ 0 | $ 0 |
| Maturity period of short term investments | Beyond 90 days | |||
| Stated maturity period of short term investments | One year or more | |||