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Basis of Presentation and Significant Accounting Policies - Fair Value of Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) (USD $)
In Thousands, unless otherwise specified |
Jun. 30, 2013
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Dec. 31, 2012
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|---|---|---|
| Assets: | ||
| Money market funds | $ 179,572 | $ 239,443 |
| Liabilities: | ||
| Contingent consideration obligations | 443 | 392 |
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Level 1 [Member]
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| Assets: | ||
| Money market funds | 179,572 | 239,443 |
| Liabilities: | ||
| Contingent consideration obligations | ||
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Level 2 [Member]
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||
| Assets: | ||
| Money market funds | ||
| Liabilities: | ||
| Contingent consideration obligations | ||
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Level 3 [Member]
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| Assets: | ||
| Money market funds | ||
| Liabilities: | ||
| Contingent consideration obligations | $ 443 | $ 392 |