Equity (Details 6) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Additional share based compensation information
Unrecognized compensation expense on awards not expected to vest	$ 3.0
Additional paid-in capital
Additional share based compensation information
Unrecognized stock-based compensation expense	21.3
Restricted shares with service and performance features
Shares
Non-vested at the end of the period (in shares)	0.3
Performance-based awards
Shares
Non-vested at the end of the period (in shares)	0.1
Estimated amortization of share based compensation expense
Amortized compensation expense attributable to stock option and restricted stock grants		2.5
Restricted stock awards
Shares
Non-vested at the beginning of the period (in shares)	1.0	1.2	0.6
Granted (in shares)	0.4	0.1	0.6
Vested (in shares)	(0.7)	(0.2)
Forfeited (in shares)	(0.1)	(0.1)
Non-vested at the end of the period (in shares)	0.6	1.0	1.2
Weighted Average Grant Date Fair Value
Non-vested at the beginning of the period (in dollars per share)	$ 48.52	$ 50.62	$ 53.17
Granted (in dollars per share)	$ 67.65	$ 44.39	$ 47.94
Vested (in dollars per share)	$ 42.34	$ 52.89
Forfeited (in dollars per share)	$ 71.16	$ 47.09
Non-vested at the end of the period (in dollars per share)	$ 62.19	$ 48.52	$ 50.62
Additional share based compensation information
Grant date fair value of restricted stock awards vested	31.5	11.5	2.1
Stock option and restricted stock grants \| 2014
Estimated amortization of share based compensation expense
Amortized compensation expense attributable to stock option and restricted stock grants	10.1
Stock option and restricted stock grants \| 2015
Estimated amortization of share based compensation expense
Amortized compensation expense attributable to stock option and restricted stock grants	7.2
Stock option and restricted stock grants \| 2016
Estimated amortization of share based compensation expense
Amortized compensation expense attributable to stock option and restricted stock grants	$ 1.0

Employee Service Share-based Compensation, Nonvested Awards Not Expected to Vest, Compensation Cost Not yet Recognized

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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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Unrecognized cost of unvested share-based compensation awards.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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