Cleveland-Cliffs Inc. Annual report pursuant to Section 13 and 15(d)

Pensions And Other Postretirement Benefits (Effect Of Fair Value Measurements Using Significant Unobservable Inputs (Level 3) On Changes In Pension Plan Assets) (Details)

Pensions And Other Postretirement Benefits (Effect Of Fair Value Measurements Using Significant Unobservable Inputs (Level 3) On Changes In Pension Plan Assets) (Details) (Significant Unobservable Inputs (Level 3) [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	$ 186.0	$ 143.1
Relating to assets still held at the reporting date	7.0	7.8
Acquired through business combinations	40.2	17.0
Relating to assets sold during the period	4.0	0.1
Purchases, sales and settlements		18.0
Purchases	40.2	17.0
Sales	(45.0)
Ending balance	192.2	186.0
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	105.8	71.4
Relating to assets still held at the reporting date	(2.4)	2.4
Acquired through business combinations	35.8	17.0
Relating to assets sold during the period	0.5
Purchases, sales and settlements		15.0
Purchases	35.8	17.0
Sales	(39.0)
Ending balance	100.7	105.8
Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	25.0	18.2
Relating to assets still held at the reporting date	2.6	3.4
Acquired through business combinations	4.4
Relating to assets sold during the period	3.0	0.1
Purchases, sales and settlements		3.3
Purchases	4.4
Sales	(4.9)
Ending balance	30.1	25.0
Structured Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	39.7	39.1
Relating to assets still held at the reporting date	5.2	0.5
Purchases, sales and settlements		0.1
Ending balance	44.9	39.7
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	15.5	14.4
Relating to assets still held at the reporting date	1.6	1.5
Relating to assets sold during the period	0.5
Purchases, sales and settlements		(0.4)
Sales	(1.1)
Ending balance	$ 16.5	$ 15.5

- Definition

The amount of increase in the plan assets attributed to a business combination.

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- Definition

The amount of decrease in the plan assets attributed to the sale, liquidation, spin-off or other divestiture of a corporate division or subsidiary.

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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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