Stock-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 279.5	$ 281.3	$ 255.3
Tax benefit	$ 58.7	$ 70.5	$ 89.4
Number of shares available for grant (in shares)	53.3
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	2 years
Weighted average grant date fair value (in usd per share)	$ 71.63	$ 73.54	$ 72.00
Shares issued in period (in shares)	0.9	1.3	0.5
Shares expected to be issued (in shares)	1.2
Total compensation cost not yet recognized	$ 63.7
Period for recognition of the compensation cost not yet recognized (in months)	12 months
Shareholder Value Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Weighted average grant date fair value (in usd per share)	$ 48.51	$ 66.25	$ 48.68
Shares issued in period (in shares)	0.7	1.1	1.0
Shares expected to be issued (in shares)	1.0
Total compensation cost not yet recognized	$ 55.7
Period for recognition of the compensation cost not yet recognized (in months)	20 months
Expected dividend yield (in percentage)	2.50%	2.50%	2.00%
Risk-free interest rate (in percentage)	2.31%	1.38%	0.92%
Volatility (in percentage)	22.26%	22.91%	21.68%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)	3 years
Weighted average grant date fair value (in usd per share)	$ 70.95	$ 72.47	$ 71.46
Shares issued in period (in shares)	1.0	0.9	0.6
Shares expected to be issued (in shares)	0.8
Total compensation cost not yet recognized	$ 112.2
Period for recognition of the compensation cost not yet recognized (in months)	21 months
Grants in period (in shares)	1.3	1.4	1.3

The number of shares expected to be issued in the next twelve months under the plan.

No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

Number of share instruments newly issued under a share-based compensation plan.

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