| CONSOLIDATED STATEMENT OF CHANGES IN EQUITY AND OTHER COMPREHENSIVE INCOME (Unaudited) (Parenthetical) $ in Millions | 3 Months Ended | 9 Months Ended | 
|---|---|---|
| Sep. 30, 2018  USD ($)  $ / shares | Sep. 30, 2018  USD ($)  $ / shares | |
| Statement of Stockholders' Equity [Abstract] | ||
| Cash dividends, per share (in dollars per share) | $ / shares | $ 0.39 | $ 1.17 | 
| Common stock authorized, amount for future purchases | $ | $ 590.1 | $ 590.1 | 
| X | ||||||||||
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- Definition Aggregate dividends paid during the period for each share of common stock outstanding. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
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- References No definition available. 
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| X | ||||||||||
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- Definition Amount of stock repurchase plan authorized. No definition available. 
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