Pensions And Other Postretirement Benefits (Fair Value Of Plan Assets, Benefit Obligation And Funded Status) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 744.1	$ 734.3	$ 483.4
Benefit obligations	(1,141.4)	(1,022.3)	(750.8)
Funded status (plan assets less benefit obligations)	(397.3)	(288.0)
Pension Benefits [Member] \| Salaried Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	289.1	275.3
Benefit obligations	(419.3)	(373.8)
Funded status (plan assets less benefit obligations)	(130.2)	(98.5)
Pension Benefits [Member] \| Hourly Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	451.8	456.7
Benefit obligations	(708.0)	(635.3)
Funded status (plan assets less benefit obligations)	(256.2)	(178.6)
Pension Benefits [Member] \| Mining Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.2	2.3
Benefit obligations	(5.3)	(4.4)
Funded status (plan assets less benefit obligations)	(2.1)	(2.1)
Pension Benefits [Member] \| Supplemental Executive Retirement Plan SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations	(8.8)	(8.8)
Funded status (plan assets less benefit obligations)	(8.8)	(8.8)
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	193.5	174.2	136.7
Benefit obligations	(488.4)	(440.2)	(333.0)
Funded status (plan assets less benefit obligations)	(294.9)	(266.0)
Other Benefits [Member] \| Salaried Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations	(70.7)	(63.7)
Funded status (plan assets less benefit obligations)	(70.7)	(63.7)
Other Benefits [Member] \| Hourly Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	193.5	174.2
Benefit obligations	(417.7)	(376.5)
Funded status (plan assets less benefit obligations)	$ (224.2)	$ (202.3)

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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Projected Benefit Obligation

-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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph a

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 6

-Subparagraph a

-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 Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph E1

-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.

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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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