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           Stock Repurchase Programs (Details) (USD $) 
        In Millions, except Share data, unless otherwise specified  | 
        1 Months Ended | 6 Months Ended | |
|---|---|---|---|
| 
           Nov. 30, 2011 
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           Mar. 31, 2013 
         | 
        
           Mar. 31, 2012 
         | 
      |
| Stock Repurchase Programs | |||
| Stock repurchase programs, authorized amount | $ 125.0 | ||
| Common shares repurchased | 249,549 | 236,700 | |
| Common shares repurchased, cost | 14.6 | 8.8 | |
| Amount remaining available for future stock repurchases | $ 114.6 | ||
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- Details 
          
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- Definition 
          The amount authorized by an entity's Board of Directors under a stock repurchase plan. No definition available. 
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- Definition 
          The remaining repurchase amount authorized by an entity's Board of Directors under a stock repurchase plan. No definition available. 
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- Definition 
          Number of shares that have been repurchased during the period and are being held in treasury. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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