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Share-Based Compensation (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Recent share based compensation expense
Share Based Compensation Expense	$ 47.6	$ 30.3	$ 19.5
Tax Benefit	18.2	11.6	7.5
Compensation expense related to share-based compensation	$ 78.4	$ 80.0
Weighted average period over which compensation expense will be recognized	3 years	3 years
Stock Option and Incentive Plan
Options granted
Weighted average fair value of options granted (in dollars per share)	$ 40.43	$ 30.27	$ 23.54
Assumptions used to determine fair value of options granted
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Expected volatility (as a percent)	36.80%	33.10%	32.40%
Risk-free interest rate (as a percent)	0.70%	1.30%	1.60%
Expected life of options	5 years	4 years 9 months 18 days	4 years 6 months
Forfeiture rate (as a percent)	1.40%	2.40%	4.80%

X

- Definition

Represents the expected rate the entity will cancel the stock option awards due to nonfulfillment of certain conditions of equity-based compensation arrangements.

+ References

No definition available.

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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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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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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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- Definition

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

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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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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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