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ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Summary Of Mine Closure Obligations) (Details) - USD ($) $ in Millions | Sep. 30, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | ---
Loss Contingencies [Line Items] |  |  |
Environmental | $ 2.1 | $ 2.5 |
Asset Retirement Obligation | 179.5 | 172.4 | $ 168.4
Mine Reclamation and Closing Liability, current and noncurrent | 181.6 | 174.9 |
Accrued Reclamation Costs, Current | 2.5 | 2.9 |
ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS | 179.1 | 172.0 |
Mining and Pelletizing [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Asset Retirement Obligation | $ 179.5 | $ 172.4 |

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 + Details
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- Definition Current portion of reclamation reserve to restore a mining or drilling site to the condition agreed upon within the mining or drilling contract. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6911-107765 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of a reclamation and mine closing liability that is associated with a legal obligation for the closure and reclamation of a mine including the removal of buildings, equipment, machinery and other physical remnants of mining, closure of tailings impoundments, leach pads and other mine features, and contouring, covering and revegetation of waste rock piles and other disturbed areas. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.Y.Q2) -URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751 + Details
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