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Employee Benefit Plans Amounts Charged to Income for employees Incentive Compensation Plans (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Incentive Compensation Cash Award |  |  |
Incentive Compensation Plans Expense [Line Items] |  |  |
Pretax | $ 461.3 | $ 386.8 | $ 337.7
After Tax | 299.8 | 251.4 | 219.5
Employee Stock [Member] |  |  |
Incentive Compensation Plans Expense [Line Items] |  |  |
Pretax | 92.9 | 80.9 | 64.5
After Tax | 60.4 | 52.6 | 41.9
Employee Stock Option |  |  |
Incentive Compensation Plans Expense [Line Items] |  |  |
Pretax | 2.5 | 4.3 | 1.7
After Tax | $ 1.6 | $ 2.8 | $ 1.1

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- Definition Incentive Compensation Expenses + References No definition available. + Details
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- Definition Incentive Compensation Expenses Net of Tax + References No definition available. + Details
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- Definition Incentive Compensation Plans Expense [Line Items] + References No definition available. + Details
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- Details
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- Details
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- Details
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