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Equity Method Investments Financing Receivables (Tables) | 3 Months Ended
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Mar. 31, 2019
Financing Receivables [Abstract] |
Equity Method Investments [Table Text Block] | Middlemount’s standalone results include (on a 50% attributable basis):
| Three Months Ended March 31,
| 2019 |  | 2018
| (Dollars in millions)
Depreciation, depletion and amortization and asset retirement obligation expenses | $ | 3.6 |  |  | $ | 3.9 |
Net interest expense | 2.2 |  |  | 3.6 |
Income tax provision | 1.7 |  |  | 5.1 |

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- Definition Tabular disclosure of equity method investments including, but not limited to, name of each investee or group of investments, percentage ownership, difference between recorded amount of an investment and the value of the underlying equity in the net assets, and summarized financial information. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571 + Details
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