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Summary of Significant Accounting Policies - Fair Value Hierarchy for Financial Assets (Detail) (USD $)
In Thousands, unless otherwise specified |
Sep. 29, 2012
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Dec. 31, 2011
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|---|---|---|
| Fair value hierarchy for financial assets | ||
| Total | $ 69,620 | $ 69,137 |
|
U.S. Treasuries [Member]
|
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| Fair value hierarchy for financial assets | ||
| Total | 67,993 | 67,800 |
|
Money Market Funds [Member]
|
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| Fair value hierarchy for financial assets | ||
| Total | 1,627 | 1,337 |
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Level 1 [Member]
|
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| Fair value hierarchy for financial assets | ||
| Total | 69,620 | 69,137 |
|
Level 1 [Member] | U.S. Treasuries [Member]
|
||
| Fair value hierarchy for financial assets | ||
| Total | 67,993 | 67,800 |
|
Level 1 [Member] | Money Market Funds [Member]
|
||
| Fair value hierarchy for financial assets | ||
| Total | 1,627 | 1,337 |
|
Level 2 [Member]
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||
| Fair value hierarchy for financial assets | ||
| Total | ||
|
Level 2 [Member] | U.S. Treasuries [Member]
|
||
| Fair value hierarchy for financial assets | ||
| Total | ||
|
Level 2 [Member] | Money Market Funds [Member]
|
||
| Fair value hierarchy for financial assets | ||
| Total | ||
|
Level 3 [Member]
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| Fair value hierarchy for financial assets | ||
| Total | ||
|
Level 3 [Member] | U.S. Treasuries [Member]
|
||
| Fair value hierarchy for financial assets | ||
| Total | ||
|
Level 3 [Member] | Money Market Funds [Member]
|
||
| Fair value hierarchy for financial assets | ||
| Total |