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

SEGMENT REPORTING Segment Reporting (Summary of Assets by Segment) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Assets	$ 3,164.0us-gaap_Assets	$ 13,121.9us-gaap_Assets	$ 13,574.9us-gaap_Assets
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	1,598.3	1,671.6	1,735.1
Eastern Canadian Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	305.8	7,915.5	7,605.1
Asia Pacific Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	274.6	1,078.4	1,506.3
North American Coal [Member]
Segment Reporting Information [Line Items]
Assets	274.2	1,841.8	1,877.8
All Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	164.3	455.6	570.9
Total Segment Assets [Member]
Segment Reporting Information [Line Items]
Assets	2,617.2	12,962.9	13,295.2
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	$ 546.8	$ 159.0	$ 279.7