Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock-based compensation costs
Compensation costs related to stock-based compensation, pre-tax	$ 28.6	$ 24.7	$ 26.0
Compensation costs related to stock-based compensation, after-tax	19.9	17.8	19.1
Total compensation cost related to nonvested awards not yet recognized	35.0	40.1
Maximum
Stock-based compensation costs
Vesting period	5 years
Restricted stock
Stock-based compensation
Outstanding at the beginning of the period (in shares)	355,289	494,066	552,690
Awarded (in shares)		97,005	165,110
Released (in shares)	(144,762)	(234,772)	(203,734)
Canceled (in shares)		(1,010)	(20,000)
Outstanding at the end of the period (in shares)	210,527	355,289	494,066
Stock-based compensation costs
Total compensation cost related to nonvested awards not yet recognized	1.7	5.9
Stock options
Stock-based compensation costs
Total compensation cost related to nonvested awards not yet recognized	33.3	34.2
Phantom stock unit awards
Stock-based compensation costs
Compensation costs related to stock-based compensation, pre-tax	5.9	2.1	0.4
Total compensation cost related to nonvested awards not yet recognized	13.8
Period for recognition of unrecognized compensation cost	2 years 10 months 17 days
Phantom stock unit awards \| Minimum
Stock-based compensation costs
Vesting period	4 years
Phantom stock unit awards \| Maximum
Stock-based compensation costs
Vesting period	5 years
Stock appreciation rights
Stock-based compensation costs
Compensation costs related to stock-based compensation, pre-tax	4.4	1.4
Total compensation cost related to nonvested awards not yet recognized	$ 11.4
Period for recognition of unrecognized compensation cost	2 years 9 months
Vesting period	4 years

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(1)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph g(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

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-URI http://asc.fasb.org/extlink&oid=6793087&loc=d3e301413-122809

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The amount of expense, net of income tax, 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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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 equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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

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