Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Equity (Schedule Of Stockholders' Equity) (Detail)

v2.4.0.6
Shareholders' Equity (Schedule Of Stockholders' Equity) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Balance     $ 5,785.0  
Balance     1,254.7  
Balance     7,039.7 3,838.7
Net income 85.1 601.2 719.0 1,433.6
Net income 6.7 (151.8) (25.2) (170.1)
Net income 78.4 753.0 744.2 1,603.7
Other comprehensive income 123.9 446.0 760.6 1,328.4
Other comprehensive income 40.3 (155.6) 46.1 (104.7)
Total comprehensive income (1.5) 0.4 (4.5) (0.5)
Total comprehensive income     790.3 1,499.0
Share buyback   (222.0)   (221.9)
Equity offering       853.7
Purchase of additional noncontrolling interest       0.3
Stock and other incentive plans     9.0 8.8
Common stock dividends     (217.8) (78.8)
Purchase of subsidiary shares from noncontrolling interest       4.5
Undistributed gains to noncontrolling interest     11.3 12.6
Capital contribution by noncontrolling interest to subsidiary     64.7 0.3
Acquisition of controlling interest     (8.0) 947.6
Balance 6,336.8   6,336.8  
Balance 1,352.4   1,352.4  
Balance 7,689.2 6,864.8 7,689.2 6,864.8
Cliffs Shareholders' Equity [Member]
       
Balance     5,785.0 3,845.9
Net income     719.0 1,433.6
Other comprehensive income     41.6 (105.2)
Total comprehensive income     760.6 1,328.4
Share buyback       (221.9)
Equity offering       853.7
Purchase of additional noncontrolling interest       0.3
Stock and other incentive plans     9.0 8.8
Common stock dividends     (217.8) (78.8)
Purchase of subsidiary shares from noncontrolling interest       0
Undistributed gains to noncontrolling interest     0 0
Capital contribution by noncontrolling interest to subsidiary     0 0
Acquisition of controlling interest     0 0
Balance 6,336.8 5,736.4 6,336.8 5,736.4
Non-controlling Interest [Member]
       
Balance     1,254.7 (7.2)
Net income     25.2 170.1
Other comprehensive income     4.5 0.5
Total comprehensive income     29.7 170.6
Share buyback       0
Equity offering       0
Purchase of additional noncontrolling interest       0
Stock and other incentive plans     0 0
Common stock dividends     0 0
Purchase of subsidiary shares from noncontrolling interest       4.5
Undistributed gains to noncontrolling interest     11.3 12.6
Capital contribution by noncontrolling interest to subsidiary     64.7 0.3
Acquisition of controlling interest     (8.0) 947.6
Balance $ 1,352.4 $ 1,128.4 $ 1,352.4 $ 1,128.4
Bloom Lake [Member]
       
Ownership interest, percent 75.00% 75.00% 75.00% 75.00%
Tilden [Member]
       
Ownership interest, percent 85.00% 85.00% 85.00% 85.00%
Empire [Member]
       
Ownership interest, percent 79.00% 79.00% 79.00% 79.00%