Share-based Compensation Awards (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock-settled awards
Stock-based Payment Award
Stock based awards expected to be settled in cash	1.2	1.1	0.9
Weighted-average grant-date fair value (per award)	$ 17.77	$ 13.51	$ 11.43
Total fair value of vested awards distributed	$ 12.6	$ 35.4	$ 63.5
Accrued dividends on non-vested stock-settled awards	0.8	0.7
Dividends paid for stock-settled awards	0.5	1.5
Cash-settled awards
Stock-based Payment Award
Stock based awards expected to be settled in cash	0.1	0.1	0.1
Weighted-average grant-date fair value (per award)	$ 18.20	$ 16.35	$ 10.94
Total fair value of vested awards distributed	0.6	5.4	11.1
Performance-based awards
Stock-based Payment Award
Stock based awards expected to be settled in cash	3.5	1.5	1.8
Weighted-average grant-date fair value (per award)	$ 16.56	$ 11.97	$ 10.61
Total fair value of vested awards distributed	15.3	0.2	11.5
Performance based cash awards settled in shares
Stock-based Payment Award
Total fair value of vested awards distributed	$ 19.8	$ 17.4

Dividends paid for stock-settled awards vested during the period.

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- Definition

Stock based awards expected to be settled in cash

+ References

No definition available.

+ Details

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- Definition

Amount of paid and unpaid stock dividends declared and applicable to holders of share-based compensation, for example, but not limited to, non-vested shares, stock options, or restricted stock units.

+ References

No definition available.

+ Details

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- Definition

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).

+ 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 (c)(2)(iii)(1)

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

+ Details

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- Definition

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.

+ 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 (d)(2)

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

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