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           Segment Information - Additional Information (Detail) 
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           Mar. 31, 2012
 
          Segment 
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|---|---|
| Segment Reporting Disclosure [Line Items] | |
| Number of reportable segments | 5 | 
| X | ||||||||||
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- Definition 
          Number of Operating Segments No definition available. 
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| X | ||||||||||
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- Details 
          
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