Stock-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Stock-Based Compensation Activity
Income tax benefit	$ 0.5	$ 0.6	$ 2.3	$ 2.2
Performance Shares [Member]
Stock-Based Compensation Activity
Compensation expense	1.1	2.1	6.0	8.1
Restricted Stock [Member]
Stock-Based Compensation Activity
Compensation expense	0.0	0.0	0.1	0.1
Stock Compensation Plan [Member]
Stock-Based Compensation Activity
Compensation expense	1.1	2.1	6.1	8.2
Less: Amount paid by unconsolidated affiliates	(0.2)	0.6	0.3	2.5
Net compensation expense	$ 1.3	1.5	$ 5.8	5.7
Common Stock
Stock-Based Compensation Activity
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	912		81,865
Restricted Stock [Member]
Stock-Based Compensation Activity
Shares Paid for Tax Withholding for Share Based Compensation	0		1,070
Total Shareholder Return [Member] \| Performance Shares [Member]
Stock-Based Compensation Activity
Compensation expense	$ 1.9	2.0	$ 5.7	5.9
Performance Units Related to Earnings Per Share [Member] \| Performance Shares [Member]
Stock-Based Compensation Activity
Compensation expense	$ (0.8)	$ 0.1	$ 0.3	$ 2.2

Allocated Share-Based Compensation Expense, Net of Unconsolidated Affiliates

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- Definition

Amount Attributable to Unconsolidated Affiliates

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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.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 14.F)

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-Topic 718

-SubTopic 10

-Section 50

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-Section 50

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

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

+ References

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)

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

+ References

No definition available.

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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