Quarterly report pursuant to Section 13 or 15(d)

SUPPLEMENTARY GUARANTOR INFORMATION (Supplementary Statements of Condensed Consolidating Cash Flows) (Details)

v3.19.2
SUPPLEMENTARY GUARANTOR INFORMATION (Supplementary Statements of Condensed Consolidating Cash Flows) (Details) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Net cash provided (used) by operating activities $ 151.1 $ (49.3)    
Purchase of property, plant and equipment (294.4) (42.1)    
Deposits for property, plant and equipment (6.5) (72.3)    
Intercompany investing 0.0 0.0    
Proceeds on sales of assets 0.0 14.6    
Other investing activities 8.5 0.0    
Net cash used by investing activities (292.4) (99.8)    
Repurchase of common shares (252.9) 0.0    
Dividends paid (28.9) 0.0    
Proceeds from issuance of debt 720.9 0.0    
Debt issuance costs (6.8) (1.5)    
Repurchase of debt (729.3) (15.3)    
Intercompany financing 0.0 0.0    
Other financing activities (10.9) (8.9)    
Net cash used by financing activities (307.9) (25.7)    
EFFECT OF EXCHANGE RATE CHANGES ON CASH 0.0 (1.0)    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN OTHER CURRENT ASSETS RELATED TO DISCONTINUED OPERATIONS (449.2) (175.8)    
DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 3.2 0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN CURRENT ASSETS OF DISCONTINUED OPERATIONS (446.0) (175.8)    
Cash and cash equivalents 377.2 802.5 $ 823.2 $ 978.3
Reportable Legal Entities [Member] | Cliffs Shareholders Equity [Member]        
Net cash provided (used) by operating activities 20.1 (82.1)    
Purchase of property, plant and equipment (1.2) (0.3)    
Deposits for property, plant and equipment 0.0 0.0    
Intercompany investing (153.3) (35.2)    
Proceeds on sales of assets   0.0    
Other investing activities 0.0      
Net cash used by investing activities (154.5) (35.5)    
Repurchase of common shares (252.9)      
Dividends paid (28.9)      
Proceeds from issuance of debt 720.9      
Debt issuance costs (6.8) (1.5)    
Repurchase of debt (729.3) (15.3)    
Intercompany financing 0.0 (14.6)    
Other financing activities (14.2) (1.5)    
Net cash used by financing activities (311.2) (32.9)    
EFFECT OF EXCHANGE RATE CHANGES ON CASH   0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN OTHER CURRENT ASSETS RELATED TO DISCONTINUED OPERATIONS (445.6) (150.5)    
DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 0.0 0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN CURRENT ASSETS OF DISCONTINUED OPERATIONS (445.6) (150.5)    
Cash and cash equivalents 374.2 798.4 819.8 948.9
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]        
Net cash provided (used) by operating activities 134.0 83.5    
Purchase of property, plant and equipment (293.2) (41.8)    
Deposits for property, plant and equipment (6.3) (67.6)    
Intercompany investing (1.2) (5.5)    
Proceeds on sales of assets   0.4    
Other investing activities 8.4      
Net cash used by investing activities (292.3) (114.5)    
Repurchase of common shares 0.0      
Dividends paid 0.0      
Proceeds from issuance of debt 0.0      
Debt issuance costs 0.0 0.0    
Repurchase of debt 0.0 0.0    
Intercompany financing 152.9 31.5    
Other financing activities 5.1 (1.0)    
Net cash used by financing activities 158.0 30.5    
EFFECT OF EXCHANGE RATE CHANGES ON CASH   0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN OTHER CURRENT ASSETS RELATED TO DISCONTINUED OPERATIONS (0.3) (0.5)    
DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 0.0 0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN CURRENT ASSETS OF DISCONTINUED OPERATIONS (0.3) (0.5)    
Cash and cash equivalents 0.4 1.6 0.7 2.1
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]        
Net cash provided (used) by operating activities (3.0) (50.7)    
Purchase of property, plant and equipment 0.0 0.0    
Deposits for property, plant and equipment (0.2) (4.7)    
Intercompany investing 0.0 14.6    
Proceeds on sales of assets   14.2    
Other investing activities 0.1      
Net cash used by investing activities (0.1) 24.1    
Repurchase of common shares 0.0      
Dividends paid 0.0      
Proceeds from issuance of debt 0.0      
Debt issuance costs 0.0 0.0    
Repurchase of debt 0.0 0.0    
Intercompany financing 1.6 9.2    
Other financing activities (1.8) (6.4)    
Net cash used by financing activities (0.2) 2.8    
EFFECT OF EXCHANGE RATE CHANGES ON CASH   (1.0)    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN OTHER CURRENT ASSETS RELATED TO DISCONTINUED OPERATIONS (3.3) (24.8)    
DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 3.2 0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN CURRENT ASSETS OF DISCONTINUED OPERATIONS (0.1) (24.8)    
Cash and cash equivalents 2.6 2.5 2.7 27.3
Consolidation, Eliminations [Member]        
Net cash provided (used) by operating activities 0.0 0.0    
Purchase of property, plant and equipment 0.0 0.0    
Deposits for property, plant and equipment 0.0 0.0    
Intercompany investing 154.5 26.1    
Proceeds on sales of assets   0.0    
Other investing activities 0.0      
Net cash used by investing activities 154.5 26.1    
Repurchase of common shares 0.0      
Dividends paid 0.0      
Proceeds from issuance of debt 0.0      
Debt issuance costs 0.0 0.0    
Repurchase of debt 0.0 0.0    
Intercompany financing (154.5) (26.1)    
Other financing activities 0.0 0.0    
Net cash used by financing activities (154.5) (26.1)    
EFFECT OF EXCHANGE RATE CHANGES ON CASH   0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN OTHER CURRENT ASSETS RELATED TO DISCONTINUED OPERATIONS 0.0 0.0    
DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 0.0 0.0    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN CURRENT ASSETS OF DISCONTINUED OPERATIONS 0.0 0.0    
Cash and cash equivalents $ 0.0 $ 0.0 $ 0.0 $ 0.0