Retirement Benefit Plans (Schedule of defined benefit plan obligations and assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair value of plan assets	$ 294.6	$ 288.3
Retirement Plans [Member]
Benefit obligation	(383.3)	(336.1)	(330.2)
Fair value of plan assets	288.3	286.0
Funded status	(95.0)	(50.1)
Non-current assets	2.0	1.0
Current liabilities	0	(0.9)
Non-current liabilities	(97.0)	(50.2)
Medical Plan [Member]
Benefit obligation	(48.1)	(52.4)	(48.5)
Fair value of plan assets	8.2	8.1
Funded status	(39.9)	(44.3)
Non-current assets	0	0
Current liabilities	(2.2)	(2.5)
Non-current liabilities	$ (37.7)	$ (41.8)

The amount for overfunded plans recognized in the balance sheet as a noncurrent asset associated with a defined benefit pension plan or other postretirement defined benefit plan.

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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

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

Reference 2: 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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-Name Statement of Financial Accounting Standard (FAS)

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

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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- Definition

For a classified balance sheet, the amount recognized in balance sheet as a current liability associated with an underfunded defined benefit plan.

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- Definition

This represents the noncurrent liability for underfunded plans recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement defined benefit plans.

+ References

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