| CONSOLIDATED STATEMENTS OF SHAREHOLDERS EQUITY AND OTHER COMPREHENSIVE INCOME (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010 | |
| Cash dividends, per share | $ 0.72 | $ 0.64 | $ 0.28 | 
| Common stock authorized amount for future purchases | $ 227.1 | ||
| Common Stock Repurchase Program | |||
| Treasury stock purchased, per share | $ 45.73 | $ 34.19 | $ 32.28 | 
| Executive Life Insurance Benefit Trust | |||
| Shares reclassified from Stock Held by Employee Benefits Trusts to Treasury Stock | 1,500,000 | 1,500,000 | |
| X | ||||||||||
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- Definition Common Stock Shares Held in Treasury No definition available. 
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| X | ||||||||||
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- Definition Aggregate dividends paid during the period for each share of common stock outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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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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| X | ||||||||||
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- Definition Total cost of shares repurchased divided by the total number of shares repurchased. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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