Retirement Benefits - Schedule of Change in Benefit Obligations (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Compensation and Retirement Disclosure [Abstract]
Benefit obligation, beginning of period	$ 46.0	$ 52.7	$ 52.7	$ 46.8
Service cost	1.1us-gaap_DefinedBenefitPlanServiceCost	1.3us-gaap_DefinedBenefitPlanServiceCost	1.7us-gaap_DefinedBenefitPlanServiceCost	1.5us-gaap_DefinedBenefitPlanServiceCost	1.3us-gaap_DefinedBenefitPlanServiceCost
Interest cost	1.9us-gaap_DefinedBenefitPlanInterestCost	1.5us-gaap_DefinedBenefitPlanInterestCost	2.0us-gaap_DefinedBenefitPlanInterestCost	2.2us-gaap_DefinedBenefitPlanInterestCost	2.2us-gaap_DefinedBenefitPlanInterestCost
Actuarial gain (loss)			(5.1)	2.7
Benefits paid			(1.6)us-gaap_DefinedBenefitPlanBenefitsPaid	(2.2)us-gaap_DefinedBenefitPlanBenefitsPaid
Cumulative translation adjustments			(3.7)	1.7
Benefit obligation, end of period			$ 46.0	$ 52.7	$ 46.8

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Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Gain or Loss

-URI http://asc.fasb.org/extlink&oid=6514294

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)(4)

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 60

-Glossary Gain or Loss

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- Definition

1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

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-Name Accounting Standards Codification

-Glossary Projected Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6522206

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Postretirement Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6503904

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- Definition

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Postretirement Benefits

-URI http://asc.fasb.org/extlink&oid=6521376

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-Topic 715

-SubTopic 60

-Section 50

-Paragraph 4

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-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Benefits

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-Subparagraph (a)(6)

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- Definition

Amount of gain (loss) from foreign currency exchange rate changes for benefit obligation for plans of a foreign operation whose functional currency is not the reporting currency.

+ References

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

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-Glossary Service Cost (Component of Net Periodic Pension Cost)

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