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Related-party Transactions - Additional Information (Detail) (USD $)
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12 Months Ended | 12 Months Ended | |
|---|---|---|---|
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Dec. 31, 2012
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Sep. 07, 2010
Philips Pension Trustees Limited [Member]
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Dec. 31, 2012
PPTL Investment LP [Member]
Transactions
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| Related Party Transaction [Line Items] | |||
| Annual advisory fee | $ 25,000 | ||
| Aggregate amount of advisory fee | $ 125,000 | ||
| Common stock purchased | 42,715,650 | 22,141,217 | |
| Number of transactions involved during acquisition | 6 |