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Fair Value Measurements and Marketable Securities - Marketable Securities with Unrealized Losses (Detail) (USD $)
In Thousands, unless otherwise specified |
Jun. 30, 2013
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|---|---|
| Schedule of Available-for-sale Securities [Line Items] | |
| Marketable securities, In loss position for less than twelve months, Fair Value | $ 50,244 |
| Marketable securities, In loss position for less than twelve months, Unrealized Loss | (37) |
|
U.S. Government securities [Member]
|
|
| Schedule of Available-for-sale Securities [Line Items] | |
| Marketable securities, In loss position for less than twelve months, Fair Value | 9,242 |
| Marketable securities, In loss position for less than twelve months, Unrealized Loss | (6) |
|
Corporate debt securities [Member]
|
|
| Schedule of Available-for-sale Securities [Line Items] | |
| Marketable securities, In loss position for less than twelve months, Fair Value | 41,002 |
| Marketable securities, In loss position for less than twelve months, Unrealized Loss | $ (31) |