Stock-Based Compensation (Details 6) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock-based awards
Share-based compensation
Weighted average contractual life remaining for exercisable shares	6 years
Total number of in-the-money options exercisable, shares	2,683,320
Aggregate intrinsic values of options exercised	$ 92.5	$ 10.7	$ 3.0
Aggregate intrinsic values of in-the-money outstanding options	239.9
Aggregate intrinsic values of in-the-money exercisable options	118.6
Market price of company's common stock (in dollars per share)	$ 75.53
Exercisable outstanding options (in shares)		3,753,124	3,314,873
Exercisable outstanding options, weighted average price (in dollars per share)		$ 30.32	$ 29.65
Restricted Stock
Summary of award activity under restricted stock and restricted stock units
Restricted Stock Awards, Shares, Beginning Balance	390,768	391,522	368,641
Weighted Average Grant Date Fair Value, Beginning Balance (in dollars per share)	$ 32.75	$ 28.91	$ 29.12
Restricted Stock Awards, Shares, Granted	282,167	232,383	250,464
Weighted Average Grant Date Fair Value, Granted (in dollars per share)	$ 42.91	$ 35.03	$ 29.68
Restricted Stock Awards, Shares, Vested	(191,856)	(191,012)	(172,870)
Weighted Average Grant Date Fair Value, Vested (in dollars per share)	$ 32.09	$ 29.66	$ 28.74
Restricted Stock Awards, Shares, Cancelled	(51,711)	(42,125)	(54,713)
Weighted Average Grant Date Fair Value, Cancelled (in dollars per share)	$ 34.60	$ 30.80	$ 28.94
Restricted Stock Awards, Shares, Ending Balance	429,368	390,768	391,522
Weighted Average Grant Date Fair Value, Ending Balance (in dollars per share)	$ 39.50	$ 32.75	$ 28.91
Total fair value of restricted stock awards vested	$ 6.2	$ 5.7	$ 5.0

Share-based compensation arrangement by share based payment award options exercisable shares intrinsic value.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Price of a single share of a number of saleable stocks of a company.

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