Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.3
SUPPLEMENTARY GUARANTOR INFORMATION (Supplementary Statements of Condensed Consolidating Cash Flows) (Details) - USD ($)
$ in Millions
 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Net cash provided (used) by operating activities $ 388.1 $ 188.7    
Purchase of property, plant and equipment (447.9) (111.4)    
Deposits for property, plant and equipment (12.8) (83.3)    
Intercompany investing 0.0 0.0    
Other investing activities 11.2 21.0    
Net cash provided (used) by investing activities (449.5) (173.7)    
Repurchase of common shares (252.9) 0.0    
Dividends paid (45.1) 0.0    
Proceeds from issuance of debt 720.9 0.0    
Debt issuance costs (6.8) (1.5)    
Repurchase of debt (729.3) (16.3)    
Distributions of partnership equity (44.2) (44.2)    
Intercompany financing 0.0 0.0    
Other financing activities (9.5) (45.7)    
Net cash provided (used) by financing activities (366.9) (107.7)    
EFFECT OF EXCHANGE RATE CHANGES ON CASH 0.0 (2.3)    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN OTHER CURRENT ASSETS RELATED TO DISCONTINUED OPERATIONS (428.3) (95.0)    
LESS: DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS (4.4) (13.8)    
NET DECREASE IN CASH AND CASH EQUIVALENTS (423.9) (81.2)    
Cash and cash equivalents 399.3 897.1 $ 823.2 $ 978.3
Reportable Legal Entities [Member] | Cliffs Shareholders Equity [Member]        
Net cash provided (used) by operating activities (11.0) (100.6)    
Purchase of property, plant and equipment (1.2) (1.1)    
Deposits for property, plant and equipment 0.0 0.0    
Intercompany investing (83.6) 185.7    
Other investing activities 0.0 0.0    
Net cash provided (used) by investing activities (84.8) 184.6    
Repurchase of common shares (252.9)      
Dividends paid (45.1)      
Proceeds from issuance of debt 720.9      
Debt issuance costs (6.8) (1.5)    
Repurchase of debt (729.3) (16.3)    
Distributions of partnership equity 0.0 0.0    
Intercompany financing 0.0 (120.7)    
Other financing activities (14.6) (1.9)    
Net cash provided (used) by financing activities (327.8) (140.4)    
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 (423.6) (56.4)    
LESS: DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 0.0 0.0    
NET DECREASE IN CASH AND CASH EQUIVALENTS (423.6) (56.4)    
Cash and cash equivalents 396.2 892.5 819.8 948.9
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]        
Net cash provided (used) by operating activities 402.8 425.6    
Purchase of property, plant and equipment (446.7) (110.2)    
Deposits for property, plant and equipment (12.3) (78.1)    
Intercompany investing (1.2) (6.3)    
Other investing activities 10.4 3.1    
Net cash provided (used) by investing activities (449.8) (191.5)    
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    
Distributions of partnership equity (44.2) (44.2)    
Intercompany financing 83.1 (188.6)    
Other financing activities 7.8 (1.5)    
Net cash provided (used) by financing activities 46.7 (234.3)    
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) (0.2)    
LESS: DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 0.0 0.0    
NET DECREASE IN CASH AND CASH EQUIVALENTS (0.3) (0.2)    
Cash and cash equivalents 0.4 1.9 0.7 2.1
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]        
Net cash provided (used) by operating activities (3.7) (136.3)    
Purchase of property, plant and equipment 0.0 (0.1)    
Deposits for property, plant and equipment (0.5) (5.2)    
Intercompany investing 0.0 120.7    
Other investing activities 0.8 17.9    
Net cash provided (used) by investing activities 0.3 133.3    
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    
Distributions of partnership equity 0.0 0.0    
Intercompany financing 1.7 9.2    
Other financing activities (2.7) (42.3)    
Net cash provided (used) by financing activities (1.0) (33.1)    
EFFECT OF EXCHANGE RATE CHANGES ON CASH   (2.3)    
DECREASE IN CASH AND CASH EQUIVALENTS, INCLUDING CASH CLASSIFIED WITHIN OTHER CURRENT ASSETS RELATED TO DISCONTINUED OPERATIONS (4.4) (38.4)    
LESS: DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS (4.4) (13.8)    
NET DECREASE IN CASH AND CASH EQUIVALENTS 0.0 (24.6)    
Cash and cash equivalents 2.7 2.7 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 84.8 (300.1)    
Other investing activities 0.0 0.0    
Net cash provided (used) by investing activities 84.8 (300.1)    
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    
Distributions of partnership equity 0.0 0.0    
Intercompany financing (84.8) 300.1    
Other financing activities 0.0 0.0    
Net cash provided (used) by financing activities (84.8) 300.1    
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    
LESS: DECREASE IN CASH AND CASH EQUIVALENTS FROM DISCONTINUED OPERATIONS, CLASSIFIED WITHIN OTHER CURRENT ASSETS 0.0 0.0    
NET DECREASE IN CASH AND CASH EQUIVALENTS 0.0 0.0    
Cash and cash equivalents $ 0.0 $ 0.0 $ 0.0 $ 0.0