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Share-Based Compensation Plans - Summary of Stock Activity under DSCP (Parenthetical) (Detail) (Directors Stock Compensation Plan [Member], Chief Executive Officer [Member]) | 1 Months Ended
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Jan. 31, 2011
Directors Stock Compensation Plan [Member] | Chief Executive Officer [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Number of common stock awarded | 304

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- Definition Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Awarded To Non Employee Directors + References No definition available. + Details
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Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration