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Fair Value Measurements and Marketable Securities - Marketable Securities with Unrealized Losses (Detail) (USD $)
In Thousands, unless otherwise specified |
Sep. 30, 2014
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|---|---|
| Schedule Of Available For Sale Securities [Line Items] | |
| Marketable securities, in loss position for less than twelve months, Fair Value | $ 24,961 |
| Marketable securities, in loss position for less than twelve months, Unrealized Loss | (13) |
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U. S. Government Securities
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|
| Schedule Of Available For Sale Securities [Line Items] | |
| Marketable securities, in loss position for less than twelve months, Fair Value | 6,023 |
| Marketable securities, in loss position for less than twelve months, Unrealized Loss | (1) |
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Corporate Debt Securities
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|
| Schedule Of Available For Sale Securities [Line Items] | |
| Marketable securities, in loss position for less than twelve months, Fair Value | 18,938 |
| Marketable securities, in loss position for less than twelve months, Unrealized Loss | $ (12) |