Statements Of Condensed Consolidated Operations (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
REVENUES FROM PRODUCT SALES AND SERVICES
Product	$ 5,346.6	$ 5,520.9	$ 6,321.3
Freight and venture partners' cost reimbursements	344.8	351.8	242.6
TOTAL REVENUES	5,691.4	5,872.7	6,563.9
COST OF GOODS SOLD AND OPERATING EXPENSES	(4,542.1)	(4,700.6)	(3,953.0)
SALES MARGIN	1,149.3	1,172.1	2,610.9
OTHER OPERATING INCOME (EXPENSE)
Selling, general and administrative expenses	(231.6)	(282.5)	(248.3)
Exploration costs	(59.0)	(142.8)	(80.5)
Impairment of goodwill and other long-lived assets	(250.8)	(1,049.9)	(27.8)
Consolidated Thompson acquisition costs	0	0	(25.4)
Miscellaneous - net	63.1	(5.7)	67.9
Other operating expense	(478.3)	(1,480.9)	(314.1)
OPERATING INCOME (LOSS)	671.0	(308.8)	2,296.8
OTHER INCOME (EXPENSE)
Changes in fair value of foreign currency contracts, net	(3.5)	(0.1)	101.9
Interest expense, net	(179.1)	(195.6)	(206.2)
Other non-operating income (expense)	0.9	2.7	(2.0)
TOTAL OTHER INCOME (EXPENSE)	(181.7)	(193.0)	(106.3)
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND EQUITY INCOME (LOSS) FROM VENTURES	489.3	(501.8)	2,190.5
INCOME TAX EXPENSE	(55.1)	(255.9)	(407.7)
EQUITY INCOME (LOSS) FROM VENTURES, net of tax	(74.4)	(404.8)	9.7
INCOME (LOSS) FROM CONTINUING OPERATIONS	359.8	(1,162.5)	1,792.5
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	2.0	35.9	20.1
NET INCOME (LOSS)	361.8	(1,126.6)	1,812.6
LOSS (INCOME) ATTRIBUTABLE TO NONCONTROLLING INTEREST	51.7	227.2	(193.5)
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	413.5	(899.4)	1,619.1
PREFERRED STOCK DIVIDENDS	(48.7)	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	$ 364.8	$ (899.4)	$ 1,619.1
EARNINGS (LOSS) PER COMMON SHARE ATTRIBUTABLE TO CLIFFS SHAREHOLDERS - BASIC
Continuing operations	$ 2.39	$ (6.57)	$ 11.41
Discontinued operations	$ 0.01	$ 0.25	$ 0.14
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Basic:	$ 2.40	$ (6.32)	$ 11.55
EARNINGS (LOSS) PER COMMON SHARE ATTRIBUTABLE TO CLIFFS SHAREHOLDERS - DILUTED
Continuing operations	$ 2.36	$ (6.57)	$ 11.34
Discontinued operations	$ 0.01	$ 0.25	$ 0.14
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Diluted:	$ 2.37	$ (6.32)	$ 11.48
AVERAGE NUMBER OF SHARES (IN THOUSANDS)
Basic	151,726	142,351	140,234
Diluted	174,323	142,351	141,012
CASH DIVIDENDS DECLARED PER DEPOSITARY SHARE	$ 1.66	$ 0.00	$ 0.00
CASH DIVIDENDS DECLARED PER COMMON SHARE	$ 0.60	$ 2.16	$ 0.84