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Property, Plant, Equipment and Mine Development (Notes) | 12 Months Ended
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Dec. 31, 2016
Property, Plant, Equipment and Mine Development [Abstract] |
Property, Plant and Equipment Disclosure [Text Block] | Property, Plant, Equipment and Mine Development Property, plant, equipment and mine development, net, as of December 31, 2016 and December 31, 2015 consisted of the following:
| December 31,
| 2016 |  | 2015
| (Dollars in millions)
Land and coal interests | $ | 10,330.8 |  |  | $ | 10,503.7 |
Buildings and improvements | 1,507.6 |  |  | 1,506.0 |
Machinery and equipment | 2,130.2 |  |  | 2,280.4 |
Less: Accumulated depreciation, depletion and amortization | (5,191.9 | ) |  | (5,031.6 | )
Total, net | $ | 8,776.7 |  |  | $ | 9,258.5 |
The net book value of coal reserves totaled $5.5 billion as of December 31, 2016 and $5.7 billion as of December 31, 2015, which excludes the carrying value of acquired interests in mineral rights at certain Australian exploration properties of $1.2 billion for both years, respectively. The coal reserves include mineral rights for leased coal interests and advance royalties that had a net book value of $4.4 billion as of December 31, 2016 and $4.6 billion as of December 31, 2015. The remaining net book value of coal reserves of $1.1 billion at December 31, 2016 and December 31, 2015 relates to coal reserves held by fee ownership. Amounts attributable to coal reserves at properties where the Company was not currently engaged in mining operations or leasing to third parties and, therefore, the coal reserves were not currently being depleted, was $1.6 billion as of December 31, 2016 and $1.7 billion as of December 31, 2015.

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- Definition Property, Plant, Equipment and Mine Development [Abstract] + References No definition available. + Details
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- Definition The entire disclosure for long-lived, physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, accounting policies and methodology, roll forwards, depreciation, depletion and amortization expense, including composite depreciation, accumulated depreciation, depletion and amortization expense, useful lives and method used, income statement disclosures, assets held for sale and public utility disclosures. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.13-14) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=51717284&loc=d3e1361-107760 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=51719941&loc=d3e2921-110230 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
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