Cleveland-Cliffs Inc. Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments And Hedging Activities (Derivatives Not Designated As Hedging Instruments Disclosure) (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Amount of Gain/(Loss) Recognized in Income on Derivative	$ 240.60	$ 290.10	$ 849.90	$ 1,087.70
Customer Supply Agreements [Member] \| Product Revenues [Member]
Amount of Gain/(Loss) Recognized in Income on Derivative	53.80	25.10	124.90	93.40
Product Revenues [Member] \| Foreign Exchange Contracts [Member]
Amount of Gain/(Loss) Recognized in Income on Derivative		3.30	1.00	8.80
Foreign Exchange Contracts [Member] \| Other Income (Expense) [Member]
Amount of Gain/(Loss) Recognized in Income on Derivative	(6.20)	32.50	100.50	24.80
Product Revenues [Member] \| Provisional Pricing Arrangements [Member]
Amount of Gain/(Loss) Recognized in Income on Derivative	$ 193.00	$ 229.20	$ 623.50	$ 960.70