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Marketable Securities - Additional Information (Detail) | 3 Months Ended | 6 Months Ended
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Jun. 30, 2013 | Jun. 30, 2012 | Jun. 30, 2013 | Jun. 30, 2012
Financial Instruments And Marketable Securities [Abstract] |  |  |  |
Dollar value of transfers between levels | 0 | 0 | 0 | 0

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- Details
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- Definition Marketable Security Level Transfers + References No definition available. + Details
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