Peabody Energy (BTU) 10-Q 10 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares shares in Millions	3 Months Ended
	Mar. 31, 2018	May 04, 2018
Entity Information [Line Items]
Entity Registrant Name	PEABODY ENERGY CORP
Entity Central Index Key	1,064,728
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		125.5

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Revenues
Sales	$ 1,269.1
Other revenues	193.6
Total revenues	1,462.7
Costs and expenses
Operating costs and expenses (exclusive of items shown separately below)	1,057.2
Depreciation, depletion and amortization	169.6
Asset retirement obligation expenses	12.3
Selling and administrative expenses	37
Other operating (income) loss:
Net gain on disposals	(30.6)
Asset impairment	0
Income from equity affiliates	(22)
Operating profit	239.2
Interest expense	(36.3)
Interest income	(7.2)
Net periodic benefit costs, excluding service cost	4.5
Reorganization items, net	(12.8)
Income from continuing operations before income taxes	218.4
Income tax provision	10.1
Income from continuing operations, net of income taxes	208.3
Loss from discontinued operations, net of income taxes	(1.3)
Net income	207
Less: Series A Convertible Preferred Stock dividends	102.5
Less: Net (loss) income attributable to noncontrolling interests	(2.1)
Net income attributable to common stockholders	$ 106.6
Income from continuing operations:
Basic income per share (in dollars per share)	$ 0.84
Diluted income per share (in dollars per share)	0.83
Net income attributable to common stockholders:
Basic income per share (in dollars per share)	0.83
Diluted income per share (in dollars per share)	0.82
Dividends declared per share (in dollars per share)	$ 0.115
Predecessor
Revenues
Sales		$ 1,081.4
Other revenues		244.8
Total revenues		1,326.2
Costs and expenses
Operating costs and expenses (exclusive of items shown separately below)		950.2
Depreciation, depletion and amortization		119.9
Asset retirement obligation expenses		14.6
Selling and administrative expenses		36.3
Other operating (income) loss:
Net gain on disposals		(22.8)
Asset impairment		30.5
Income from equity affiliates		(15)
Operating profit		212.5
Interest expense		(32.9)
Interest income		(2.7)
Net periodic benefit costs, excluding service cost		14.4
Reorganization items, net		41.4
Income from continuing operations before income taxes		126.5
Income tax provision		2.2
Income from continuing operations, net of income taxes		124.3
Loss from discontinued operations, net of income taxes		(4.1)
Net income		120.2
Less: Series A Convertible Preferred Stock dividends		0
Less: Net (loss) income attributable to noncontrolling interests		4.8
Net income attributable to common stockholders		$ 115.4
Income from continuing operations:
Basic income per share (in dollars per share)		$ 6.46
Diluted income per share (in dollars per share)		6.44
Net income attributable to common stockholders:
Basic income per share (in dollars per share)		6.24
Diluted income per share (in dollars per share)		6.21
Dividends declared per share (in dollars per share)		$ 0

Unaudited Condensed Consolidat3

Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Net income	$ 207
Reclassification for realized losses on cash flow hedges (net of respective net tax provision of $0.0 and $9.1) included in net income	0
Postretirement plans and workers’ compensation obligations (net of respective net tax provision of $0.0 and $2.5)	0
Foreign currency translation adjustment	(0.8)
Other comprehensive (loss) income, net of income taxes	(0.8)
Comprehensive income	206.2
Less: Series A Convertible Preferred Stock dividends	102.5
Less: Net (loss) income attributable to noncontrolling interests	(2.1)
Comprehensive income attributable to common stockholders	$ 105.8
Predecessor
Net income		$ 120.2
Reclassification for realized losses on cash flow hedges (net of respective net tax provision of $0.0 and $9.1) included in net income		18.6
Postretirement plans and workers’ compensation obligations (net of respective net tax provision of $0.0 and $2.5)		4.4
Foreign currency translation adjustment		5.5
Other comprehensive (loss) income, net of income taxes		28.5
Comprehensive income		148.7
Less: Series A Convertible Preferred Stock dividends		0
Less: Net (loss) income attributable to noncontrolling interests		4.8
Comprehensive income attributable to common stockholders		$ 143.9

Unaudited Condensed Consolidat4

Unaudited Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Reclassification for realized losses on cash flow hedges included in net income (loss), tax provision	$ 0
Postretirement plans and workers' compensation obligations, tax provision	$ 0
Predecessor
Reclassification for realized losses on cash flow hedges included in net income (loss), tax provision		$ 9.1
Postretirement plans and workers' compensation obligations, tax provision		$ 2.5

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - Successor - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 1,416.6	$ 1,012.1
Restricted cash	0	40.1
Accounts receivable, net of allowance for doubtful accounts of $4.8 at March 31, 2018 and $4.6 at December 31, 2017	524	552.1
Inventories	265.5	291.3
Assets from coal trading activities, net	11.2	2.6
Collateral arrangements - current	109.1	0
Other current assets	251.1	291.8
Total current assets	2,577.5	2,190
Property, plant, equipment and mine development, net	5,008	5,111.9
Collateral arrangements	0	323.1
Investments and other assets	343.6	470.6
Deferred tax assets, noncurrent	85.5	85.6
Total assets	8,014.6	8,181.2
Current liabilities
Current portion of long-term debt	87.1	42.1
Liabilities from coal trading activities, net	8.8	11.7
Accounts payable and accrued expenses	1,050.6	1,191.1
Total current liabilities	1,146.5	1,244.9
Long-term debt, less current portion	1,368.1	1,418.7
Deferred income taxes	5.2	5.4
Asset retirement obligations	665.9	657
Accrued postretirement benefit costs	727.3	730
Other noncurrent liabilities	451.1	469.4
Total liabilities	4,364.1	4,525.4
Stockholders’ equity
Peabody Energy Corporation stockholders’ equity	3,609.8	3,606.4
Noncontrolling interests	40.7	49.4
Total stockholders’ equity	3,650.5	3,655.8
Total liabilities and stockholders’ equity	8,014.6	8,181.2
Preferred Stock
Stockholders’ equity
Total stockholders’ equity	0
Common Stock
Stockholders’ equity
Total stockholders’ equity	1.4
Additional Paid-in Capital
Stockholders’ equity
Additional paid-in capital	3,276.9	2,590.3
Total stockholders’ equity	3,276.9
Treasury Stock
Stockholders’ equity
Treasury stock, at cost	(351.4)	(175.9)
Total stockholders’ equity	(351.4)
Retained earnings
Stockholders’ equity
Retained earnings	682.3	613.6
Total stockholders’ equity	682.3
Accumulated Other Comprehensive Income
Stockholders’ equity
Accumulated other comprehensive income	0.6	1.4
Total stockholders’ equity	0.6
Convertible Preferred Stock
Stockholders’ equity
Preferred stock	0	576
Preferred Stock
Stockholders’ equity
Preferred stock	0	0
Series Common Stock
Stockholders’ equity
Common Stock		0
Common Stock | Common Stock
Stockholders’ equity
Common Stock	$ 1.4	$ 1

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parenthetical) - Successor - USD ($) shares in Millions, $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current assets
Allowance for doubtful accounts	$ 4.8	$ 4.6
Stockholders' equity
Treasury stock, shares (in shares)	10.2	5.8
Convertible Preferred Stock
Stockholders' equity
Preferred stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	0	50
Preferred stock, shares issued (in shares)	0	30
Preferred stock, shares outstanding (in shares)	0	13.5
Preferred Stock
Stockholders' equity
Preferred stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	100	50
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Series Common Stock
Stockholders' equity
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	50	50
Common stock, shares issued (in shares)	0	0
Common stock, shares outstanding (in shares)	0	0
Common Stock
Stockholders' equity
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	450	450
Common stock, shares issued (in shares)	137.3	111.8
Common stock, shares outstanding (in shares)	126.3	105.2

Unaudited Condensed Consolidat7

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Successor
Cash Flows From Operating Activities
Net income		$ 207
Loss from discontinued operations, net of income taxes		1.3
Income from continuing operations, net of income taxes		208.3
Adjustments to reconcile income from continuing operations, net of income taxes to net cash provided by operating activities:
Depreciation, depletion and amortization		169.6
Noncash interest expense, net		3.1
Deferred income taxes		0.7
Noncash share-based compensation		8.1
Asset impairment		0
Net gain on disposals		(30.6)
Income from equity affiliates		(22)
Foreign currency option contracts		2
Reclassification from other comprehensive earnings for terminated hedge contracts		0
Noncash reorganization items, net		(12.8)
Changes in current assets and liabilities:
Accounts receivable		117.1
Inventories		25.2
Net assets from coal trading activities		(11.6)
Other current assets		(25.6)
Accounts payable and accrued expenses		(42.5)
Collateral arrangements		214
Asset retirement obligations		7
Workers’ compensation obligations		0.3
Postretirement benefit obligations		(2.6)
Pension obligations		(32.3)
Other, net		5.3
Net cash provided by continuing operations		580.7
Net cash used in discontinued operations		(1)
Net cash provided by operating activities		579.7
Cash Flows From Investing Activities
Additions to property, plant, equipment and mine development		(53.7)
Changes in accrued expenses related to capital expenditures		(4.9)
Federal coal lease expenditures		(0.5)
Proceeds from disposal of assets, net of receivables		23
Contributions to joint ventures		(123.5)
Distributions from joint ventures		120.7
Advances to related parties		(2)
Repayments of loans from related parties		35.3
Payments for (Proceeds from) Other Investing Activities		0.8
Net cash (used in) provided by investing activities		(6.4)
Cash Flows From Financing Activities
Proceeds from long-term debt		0
Repayments of long-term debt		(8.2)
Payment of deferred financing costs		0
Common stock repurchases		(175.5)
Dividends paid		(15)
Distributions to noncontrolling interests		(6.6)
Proceeds from (Payments for) Other Financing Activities		0.2
Net cash (used in) provided by financing activities		(205.1)
Net change in cash, cash equivalents and restricted cash		368.2
Cash, cash equivalents and restricted cash at beginning of period	[1]	1,070.2
Cash, cash equivalents and restricted cash at end of period	[2]	1,438.4
Cash and cash equivalents at beginning of period		1,012.1
Restricted cash at beginning of period		40.1
Restricted cash included in investments and other assets at beginning of period		18
Cash, cash equivalents and restricted cash at beginning of period	[1]	1,070.2
Cash and cash equivalents at end of period		1,416.6
Restricted cash at end of period		0
Restricted cash included in investments and other assets at end of period		$ 21.8
Predecessor
Cash Flows From Operating Activities
Net income			$ 120.2
Loss from discontinued operations, net of income taxes			4.1
Income from continuing operations, net of income taxes			124.3
Adjustments to reconcile income from continuing operations, net of income taxes to net cash provided by operating activities:
Depreciation, depletion and amortization			119.9
Noncash interest expense, net			0.5
Deferred income taxes			1.7
Noncash share-based compensation			1.9
Asset impairment			30.5
Net gain on disposals			(22.8)
Income from equity affiliates			(15)
Foreign currency option contracts			0
Reclassification from other comprehensive earnings for terminated hedge contracts			27.6
Noncash reorganization items, net			10
Changes in current assets and liabilities:
Accounts receivable			159.3
Inventories			(47.2)
Net assets from coal trading activities			(0.5)
Other current assets			0.1
Accounts payable and accrued expenses			(64.9)
Collateral arrangements			(66.4)
Asset retirement obligations			10.2
Workers’ compensation obligations			(3.1)
Postretirement benefit obligations			0.8
Pension obligations			5.4
Other, net			(8)
Net cash provided by continuing operations			264.3
Net cash used in discontinued operations			(8.2)
Net cash provided by operating activities			256.1
Cash Flows From Investing Activities
Additions to property, plant, equipment and mine development			(32.8)
Changes in accrued expenses related to capital expenditures			(1.4)
Federal coal lease expenditures			(0.5)
Proceeds from disposal of assets, net of receivables			24.3
Contributions to joint ventures			(95.4)
Distributions from joint ventures			90.5
Advances to related parties			(0.4)
Repayments of loans from related parties			31.1
Payments for (Proceeds from) Other Investing Activities			0.3
Net cash (used in) provided by investing activities			15.1
Cash Flows From Financing Activities
Proceeds from long-term debt			1,000
Repayments of long-term debt			(2.1)
Payment of deferred financing costs			(45.4)
Common stock repurchases			0
Dividends paid			0
Distributions to noncontrolling interests			(0.1)
Proceeds from (Payments for) Other Financing Activities			(0.1)
Net cash (used in) provided by financing activities			952.3
Net change in cash, cash equivalents and restricted cash			1,223.5
Cash, cash equivalents and restricted cash at beginning of period			941.2
Cash, cash equivalents and restricted cash at end of period			2,164.7
Cash, cash equivalents and restricted cash at beginning of period			$ 941.2
[1]	The following table provides a reconciliation of “Cash, cash equivalents and restricted cash at beginning of period”:
[2]	The following table provides a reconciliation of “Cash, cash equivalents and restricted cash at end of period”:

Unaudited Condensed Consolidat8

Unaudited Condensed Consolidated Statement of Changes in Stockholders' Equity - Successor - USD ($) $ in Millions	Total	Series A Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income	Noncontrolling Interests	Convertible Preferred Stock	Common StockCommon Stock
Series A Convertible Preferred Stock									$ 576
Common Stock										$ 1
Additional Paid-in Capital				$ 2,590.3
Treasury Stock					$ (175.9)
Retained earnings						$ 613.6
Retained earnings | Retained Earnings	$ 613.6
Accumulated Other Comprehensive Income							$ 1.4
Noncontrolling Interests	49.4
Beginning Balance at Dec. 31, 2017	3,655.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments due to ASU 2014-09 | Retained Earnings	(22.5)
Beginning Balance at Dec. 31, 2017	3,655.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments due to ASU 2014-09	(22.5)					(22.5)
Net income	207					209.1		$ (2.1)
Dividends declared	(15)			0.4		(15.4)
Foreign currency translation adjustment	(0.8)						(0.8)
Series A Convertible Preferred Stock conversions	0	$ (576)	$ 0.4	678.1		(102.5)
Share-based compensation for equity-classified awards	8.1			8.1
Common stock repurchases					(175.5)
Distributions to noncontrolling interests	(6.6)							(6.6)
Ending Balance at Mar. 31, 2018	3,650.5	$ 0	$ 1.4	3,276.9	(351.4)	682.3	0.6	$ 40.7
Retained earnings | Retained Earnings	591.1
Series A Convertible Preferred Stock									$ 0
Common Stock										$ 1.4
Additional Paid-in Capital				$ 3,276.9
Treasury Stock					$ (351.4)
Retained earnings						$ 682.3
Accumulated Other Comprehensive Income							$ 0.6
Noncontrolling Interests	$ 40.7

Unaudited Condensed Consolidat9

Unaudited Condensed Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Predecessor
Postretirement plans and workers' compensation obligations, tax provision	$ 2.5

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements include the accounts of Peabody Energy Corporation (PEC) and its consolidated subsidiaries and affiliates (along with PEC, the Company or Peabody). Interests in subsidiaries controlled by the Company are consolidated with any outside stockholder interests reflected as noncontrolling interests, except when the Company has an undivided interest in an unincorporated joint venture. In those cases, the Company includes its proportionate share in the assets, liabilities, revenues and expenses of the jointly controlled entities within each applicable line item of the unaudited condensed consolidated financial statements. All intercompany transactions, profits and balances have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements and should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . In the opinion of management, these financial statements reflect all normal, recurring adjustments necessary for a fair presentation and certain prior year amounts have been reclassified for consistency with the current period presentation. Balance sheet information presented herein as of December 31, 2017 has been derived from the Company’s audited consolidated balance sheet at that date. The Company’s results of operations for the three months ended March 31, 2018 are not necessarily indicative of the results that may be expected for future quarters or for the year ending December 31, 2018 . Plan of Reorganization and Emergence from Chapter 11 Cases On April 13, 2016, PEC and a majority of its wholly owned domestic subsidiaries, as well as one international subsidiary in Gibraltar (collectively with PEC, the Debtors), filed voluntary petitions (the Bankruptcy Petitions) under Chapter 11 of Title 11 of the U.S. Code (the Bankruptcy Code) in the United States Bankruptcy Court for the Eastern District of Missouri (the Bankruptcy Court). The Debtors’ Chapter 11 cases (the Chapter 11 Cases) were jointly administered under the caption In re Peabody Energy Corporation, et al. , Case No. 16-42529. For periods subsequent to filing the Bankruptcy Petitions, the Company applied the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 852, “Reorganizations”, in preparing its consolidated financial statements. ASC 852 requires that financial statements distinguish transactions and events that are directly associated with the reorganization from the ongoing operations of the business. Accordingly, certain revenues, expenses, realized gains and losses and provisions for losses that were realized or incurred in the bankruptcy proceedings were recorded in “Reorganization items, net” in the unaudited condensed consolidated statements of operations. “Reorganization items, net” for the three months ended March 31, 2018 consisted of settlement gains of $12.8 million related to certain unsecured claims. For the three months ended March 31, 2017, “Reorganization items, net” consisted of professional fees of $42.5 million , accounts payable settlement gains of $0.7 million and interest income of $0.4 million . Professional fees are only those that were directly related to the reorganization including, but not limited to, fees associated with advisors to the Debtors, the unsecured creditors' committee and certain other secured and unsecured creditors. During the three months ended March 31, 2017 , $31.4 million of cash payments were made for "Reorganization items, net". On March 17, 2017, the Bankruptcy Court entered an order, Docket No. 2763 (the Confirmation Order), confirming the Debtors’ Second Amended Joint Plan of Reorganization of Debtors and Debtors in Possession (as further modified, the Plan). On April 3, 2017 (the Effective Date), the Debtors satisfied the conditions to effectiveness set forth in the Plan, the Plan became effective in accordance with its terms and the Debtors emerged from the Chapter 11 Cases. On the Effective Date, in accordance with ASC 852, the Company applied fresh start reporting which requires the Company to allocate its reorganization value to the fair value of assets and liabilities in conformity with the guidance for the acquisition method of accounting for business combinations. The Company was permitted to use fresh start reporting because (i) the holders of existing voting shares of the Predecessor (as defined below) company received less than 50% of the voting shares of the emerging entity upon reorganization and (ii) the reorganization value of the Company’s assets immediately prior to Plan confirmation was less than the total of all postpetition liabilities and allowed claims. Upon adoption of fresh start reporting, the Company became a new entity for financial reporting purposes, reflecting the Successor (as defined below) capital structure. As a result, a new accounting basis in the identifiable assets and liabilities assumed was established with no retained earnings or accumulated other comprehensive income (loss) for financial reporting purposes. The Company selected an accounting convenience date of April 1, 2017 for purposes of applying fresh start reporting as the activity between the convenience date and the Effective Date does not result in a material difference in the results. References to “Successor” in the financial statements and accompanying footnotes are in reference to reporting dates on or after April 2, 2017; references to “Predecessor” in the financial statements and accompanying footnotes are in reference to reporting dates through April 1, 2017 which includes the impact of the Plan provisions and the application of fresh start reporting. As such, the Company’s financial statements for the Successor will not be comparable in many respects to its financial statements for periods prior to the adoption of fresh start reporting and prior to the accounting for the effects of the Plan. For further information on the Plan and fresh start reporting, see Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 . In connection with fresh start reporting, the Company made certain prospective accounting policy elections that impact the Successor periods presented herein. The Company now classifies the amortization associated with its asset retirement obligation assets within “Depreciation, depletion and amortization” in its consolidated statements of operations, rather than within “Asset retirement obligation expenses”, as in Predecessor periods. With respect to its accrued postretirement benefit and pension obligations, the Company now records amounts attributable to prior service cost and actuarial valuation changes, as applicable, currently in earnings rather than recording such amounts within accumulated other comprehensive income and amortizing to expense over applicable time periods.

Newly Adopted Accounting Standa

Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented	3 Months Ended
	Mar. 31, 2018
Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented [Abstract]
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented Newly Adopted Accounting Standards Revenue Recognition. In May 2014, the FASB issued Accounting Standards Update (ASU) 2014-09, “Revenue from Contracts with Customers (Topic 606)”, that requires recognition of revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which a company expects to be entitled in exchange for those goods or services. The FASB has also issued several updates to ASU 2014-09. On January 1, 2018, the Company adopted ASU 2014-09 using the modified retrospective method. The new standard provides a single principles-based, five-step model to be applied to all contracts with customers, which steps are to (1) identify the contract(s) with the customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract and (5) recognize revenue when each performance obligation is satisfied. The Company recognized the cumulative effect of initially applying ASU 2014-09 as an adjustment to the opening balance of retained earnings. Revenue previously recognized under contracts completed prior to January 1, 2018 was not impacted by adoption and comparative information has not been restated. The impact of the adoption of ASU 2014-09 is expected to be immaterial to the Company’s results of operations, financial condition, and cash flows on an ongoing basis. The majority of the Company’s coal sales revenue will continue to be recognized as title and risk of loss transfer to the customer at mines and ports when coal is loaded to the transportation source, as further described in Note 3. “Revenue Recognition.” The impact of the adoption of ASU 2014-09 was limited to a long-term contract in which consideration related to the reimbursement of certain post-mining costs was recognized as costs were incurred, which differs in timing compared to the five-step model described above. The cumulative effects to the Company’s consolidated January 1, 2018 balance sheet were to reduce retained earnings for the amount of revenue that would have been deferred and to reduce long-term customer receivables, as noted in the table below: Balance at December 31, 2017 Adjustments due to ASU 2014-09 Balance at January 1, 2018 (Dollars in millions) ASSETS Investments and other assets $ 470.6 $ (22.5 ) $ 448.1 STOCKHOLDERS’ EQUITY Retained earnings 613.6 (22.5 ) 591.1 ASU 2014-09 also requires entities to disclose sufficient qualitative and quantitative information to enable financial statement users to understand the nature, amount, timing and uncertainty of revenues and cash flows arising from contracts with customers. Such disclosures are included in Note 3. “Revenue Recognition.” Classification of Certain Cash Receipts and Cash Payments . In August 2016, the FASB issued ASU 2016-15 to amend the classification of certain cash receipts and cash payments in the statement of cash flows to reduce diversity in practice. The Company retrospectively adopted all the provisions of this new standard in the first quarter of 2018. The classification requirements under the new guidance are either consistent with the Company’s current practices or are not applicable to its activities, and as such, did not have a material impact on classification of cash receipts and cash payments in the Company’s unaudited condensed consolidated statements of cash flows. Restricted Cash . In November 2016, the FASB issued ASU 2016-18, which reduces diversity in the presentation of restricted cash and restricted cash equivalents in the statement of cash flows. The Company retrospectively adopted all the provisions of this new accounting standard in the first quarter of 2018 and as a result of the new guidance, the Company will combine restricted cash with unrestricted cash and cash equivalents when reconciling the beginning and end of period balances on its statements of cash flows. The amendments also require a company to disclose information about the nature of the restrictions and amounts described as restricted cash and restricted cash equivalents. Such disclosures are included in Note 17. “Financial Instruments and Other Guarantees.” Further, as cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet, the Company reconciled these amounts to the total shown in the statement of cash flows in a tabular format within the Company’s unaudited condensed consolidated statements of cash flows. Compensation - Retirement Benefits . In March 2017, the FASB issued ASU 2017-07, which requires employers that sponsor defined benefit pension and other postretirement plans to report the service cost component in the same line item as other compensation costs and to report the other components of net periodic benefit costs (which include interest costs, expected return on plan assets, amortization of prior service cost or credits and actuarial gains and losses) separately and outside a subtotal of operating income on a retrospective basis. The guidance limiting the capitalization of net periodic benefit cost in assets to the service cost component will be applied prospectively. The Company adopted all the provisions of this new accounting standard in the first quarter of 2018. While adoption of this guidance did impact financial statement presentation, it did not materially impact the Company’s results of operations, financial condition, or cash flows. The retrospective impact to the unaudited condensed consolidated statement of operations was as follows: Predecessor Three Months Ended March 31, 2017 Before Application of Accounting Guidance Adjustment After Application of Accounting Guidance (Dollars in millions) Results of Operations Amounts Operating costs and expenses $ 963.7 $ (13.5 ) $ 950.2 Selling and administrative expenses 37.2 (0.9 ) 36.3 Operating profit 198.1 14.4 212.5 Net periodic benefit costs, excluding service cost — 14.4 14.4 Income from continuing operations before income taxes 126.5 — 126.5 Compensation - Stock Compensation. In May 2017, the FASB issued ASU 2017-09 to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The Company prospectively applied all the provisions of this new accounting standard on January 1, 2018 and there was no material impact to the Company’s financial statements. Accounting Standards Not Yet Implemented Leases. In February 2016, the FASB issued ASU 2016-02, which will require a lessee to recognize on its balance sheet a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term for leases with lease terms of more than 12 months. Consistent with current U.S. GAAP, the recognition, measurement and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance or operating lease. Additional qualitative disclosures along with specific quantitative disclosures will also be required. The new guidance will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018 (January 1, 2019 for the Company). In November 2017, the FASB voted to propose amendments to the new leases guidance to add two practical expedients. The proposed changes would allow entities to elect a simplified transition approach, and provide lessors with an option related to how lease and other related revenues are presented and disclosed. The Company is in the process of evaluating the impact of ASU 2016-02 and expects, through the addition of significant lease assets and lease liabilities to the consolidated balance sheet, ASU 2016-02 will have a material impact on the consolidated balance sheets (amount will be dependent on leases outstanding at adoption date), but is not expected to have a material impact on the consolidated statements of operations and comprehensive income (loss) of the Company. Financial Instruments - Credit Losses. In June 2016, the FASB issued ASU 2016-13 related to the measurement of credit losses on financial instruments. The pronouncement replaces the incurred loss methodology to record credit losses with a methodology that reflects the expected credit losses for financial assets not accounted for at fair value with gains and losses recognized through net income. This standard is effective for fiscal years beginning after December 15, 2019 (January 1, 2020 for the Company) and interim periods therein, with early adoption permitted for fiscal years, and interim periods therein, beginning after December 15, 2018. The Company is in the process of evaluating the impact that the adoption of this guidance will have on its results of operations, financial condition, cash flows and financial statement presentation. Derivatives and Hedging. In August 2017, the FASB issued ASU 2017-12 to amend the hedge accounting rules to simplify the application of hedge accounting guidance and better align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The guidance expands the ability to hedge nonfinancial and financial risk components, reduces complexity in fair value hedges of interest rate risk, eliminates the requirement to separately measure and report hedge ineffectiveness, as well as eases certain hedge effectiveness assessment requirements. The new guidance will be effective for fiscal years beginning after December 15, 2018 (January 1, 2019 for the Company) and interim periods therein, with early adoption permitted. The amendments to cash flow and net investment hedge relationships that exist on the date of adoption will be applied using a modified retrospective approach. The presentation and disclosure requirements will be applied prospectively. The Company is currently evaluating the impact that the adoption of this guidance will have on its results of operations, financial condition, cash flows and financial statement presentation. Leases - Land Easements. In January 2018, the FASB issued ASU 2018-01 to provide an optional transition practical expedient to not evaluate under Topic 842 existing or expired land easements that were not previously accounted for as leases under the current guidance in Topic 840. An entity that elects this practical expedient should evaluate new or modified land easements under Topic 842 beginning at the date that the entity adopts Topic 842. An entity that does not elect this practical expedient should evaluate all existing or expired land easements in connection with the adoption of the new leases requirements in Topic 842 to assess whether they meet the definition of a lease. The amendments in this update affect the amendments in ASU 2016-02. The effective date and transition requirements for the amendments are the same as the effective date and transition requirements in ASU 2016-02. The Company is in the process of evaluating the impact that the adoption of this guidance will have on its results of operations, financial condition, cash flows and financial statement presentation.

Revenues

Revenues	3 Months Ended
	Mar. 31, 2018
Revenue Recognition [Abstract]
Revenues [Text Block]	Revenue Recognition The Company accounts for revenue in accordance with ASC Topic 606, “Revenue from Contracts with Customers” (ASC 606), which the Company adopted on January 1, 2018, using the modified retrospective approach. See Note 2. “Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented” for further discussion of the adoption, including the impact on the Company’s opening balance sheet. Sales The majority of the Company’s revenue is derived from the sale of coal under a variety of long-term (those with initial terms of one year or longer and which often include price reopener and/or extension provisions), short-term (those with terms of less than one year) and spot agreements. The Company’s revenue from coal sales is realized and earned when risk of loss passes to the customer. Under the typical terms of the Company’s coal supply agreements, title and risk of loss transfer to the customer at the mine or port, where coal is loaded to the transportation source(s) that serves each of the Company’s mines. The Company incurs certain “add-on” taxes and fees on coal sales. Reported coal sales include taxes and fees charged by various federal and state governmental bodies and the freight charged on destination customer contracts. The Company’s U.S. operating platform primarily sells thermal coal to electric utilities in the U.S. under long-term contracts, with a portion sold into the seaborne markets as conditions warrant. A significant portion of the coal production from the U.S. mining segments is sold under long-term supply agreements, and customers of those segments continue to pursue long-term sales agreements in recognition of the importance of reliability, service and predictable coal prices to their operations. The terms of coal supply agreements result from competitive bidding and extensive negotiations with customers. Consequently, the terms of those agreements may vary in many respects, including price adjustment features, price reopener terms, coal quality requirements, quantity parameters, permitted sources of supply, treatment of environmental constraints, extension options, force majeure and termination and assignment provisions. The Company's Australian operating platform is primarily export focused with customers spread across several countries, while a portion of the metallurgical and thermal coal is sold within Australia. Generally, revenues from individual countries vary year by year based on electricity and steel demand, the strength of the global economy, governmental policies and several other factors, including those specific to each country. A majority of these sales are executed through annual and multi-year international coal supply agreements that contain provisions requiring both parties to renegotiate pricing periodically. Industry commercial practice, and the Company’s typical practice, is to negotiate pricing for seaborne metallurgical coal contracts on a quarterly, spot or index basis and seaborne thermal coal contracts on an annual, spot or index basis. The portion of volume priced on a shorter-term basis and index linked basis has increased in recent years. In the case of periodically negotiated pricing, the Company may deliver coal under provisional pricing until a final agreed-upon price is determined. The resulting make-whole settlements are recognized when reasonably estimable. Contract pricing is set forth on a per ton basis and revenue is generally recorded as the product of price and volume delivered. Many of the Company’s coal supply agreements contain provisions that permit the parties to adjust the contract price upward or downward at specified times. These contract prices may be adjusted based on inflation or deflation and/or changes in the factors affecting the cost of producing coal, such as taxes, fees, royalties and changes in the laws regulating the mining, production, sale or use of coal. In a limited number of contracts, failure of the parties to agree on a price under those provisions may allow either party to terminate the contract. The Company sometimes experiences a reduction in coal prices in new long-term coal supply agreements replacing some of its expiring contracts. Coal supply agreements also typically contain force majeure provisions allowing temporary suspension of performance by the Company or the customer during the duration of specified events beyond the control of the affected party. Most of the coal supply agreements contain provisions requiring the Company to deliver coal meeting quality thresholds for certain characteristics such as Btu, sulfur content, ash content, grindability and ash fusion temperature. Failure to meet these specifications could result in economic penalties, including price adjustments, the rejection of deliveries or termination of the contracts. Moreover, some of these agreements allow the Company’s customers to terminate their contracts in the event of changes in regulations affecting the industry that restrict the use or type of coal permissible at the customer’s plant or increase the price of coal beyond specified limits. Other Revenues "Other revenues" may include net revenues from coal trading activities as discussed in Note 7. “Coal Trading,” as well as coal sales revenues that were derived from the Company’s mining operations and sold through the Company’s coal trading business. Also included are revenues from customer contract-related payments, royalties related to coal lease agreements, sales agency commissions, farm income, and property and facility rentals. Royalty income generally results from the lease or sublease of mineral rights to third parties, with payments based upon a percentage of the selling price or an amount per ton of coal produced. Accounts Receivable The timing of revenue recognition, billings and cash collections results in accounts receivable from customers. Customers are invoiced as coal is shipped or at periodic intervals in accordance with contractual terms. Invoices typically include customary adjustments for the resolution of price variability related to prior shipments, such as coal quality thresholds. Payments are generally received within thirty days of invoicing. Accounts receivable, net at March 31, 2018 and December 31, 2017 consisted of the following: March 31, 2018 December 31, 2017 (Dollars in millions) Trade receivables, net $ 388.0 $ 504.2 Miscellaneous receivables, net 136.0 47.9 Accounts receivable, net $ 524.0 $ 552.1 Trade receivables, net presented above have been shown net of reserves of $0.5 million and $0.3 million as of March 31, 2018 and December 31, 2017 , respectively. Miscellaneous receivables, net presented above have been shown net of reserves of $4.3 million as of both March 31, 2018 and December 31, 2017 . Included in “Operating costs and expenses” in the unaudited condensed consolidated statements of operations was a charge for doubtful trade receivables of $0.2 million during the three months ended March 31, 2018 . No charges for doubtful accounts were recognized during the three months ended March 31, 2017 . The Company also records long-term customer receivables related to the reimbursement of certain post-mining costs which are included within “Investments and other assets” in the accompanying condensed consolidated balance sheets. The balance of such receivables was $52.9 million and $139.3 million as of March 31, 2018 and December 31, 2017 , respectively. The balance was adjusted in connection with the adoption of ASC 606, as described in Note 2. “Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented.” Also in connection with the adoption of ASC 606, the Company prospectively records a portion of the consideration received as “Interest income” rather than “Other revenues” in the accompanying unaudited condensed consolidated statements of operations, due to the embedded financing element within the related contract. Interest income related to these arrangements amounted to $2.1 million during the three months ended March 31, 2018 . Disaggregation of Revenues Revenue by product type and market is set forth in the following tables. With respect to its Australian Mining segments, the Company classifies as “Export” certain revenue from domestically-delivered coal under contracts in which the price is derived on a basis similar to export contracts. Successor Three Months Ended March 31, 2018 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Thermal coal Domestic $ 389.2 $ 200.9 $ 130.3 $ — $ 36.1 $ — $ — $ 756.5 Export — 0.7 8.0 — 164.9 — — 173.6 Total thermal 389.2 201.6 138.3 — 201.0 — — 930.1 Metallurgical coal Export — — — 465.3 — — — 465.3 Total metallurgical — — — 465.3 — — — 465.3 Other 0.1 0.1 5.4 0.9 0.4 20.1 40.3 67.3 Total revenues $ 389.3 $ 201.7 $ 143.7 $ 466.2 $ 201.4 $ 20.1 $ 40.3 $ 1,462.7 Predecessor Three Months Ended March 31, 2017 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Thermal coal Domestic $ 394.3 $ 193.2 $ 133.5 $ — $ 27.3 $ — $ — $ 748.3 Export — — — — 197.2 — — 197.2 Total thermal 394.3 193.2 133.5 — 224.5 — — 945.5 Metallurgical coal Export — — — 324.6 — — — 324.6 Total metallurgical — — — 324.6 — — — 324.6 Other — — 16.2 4.3 0.3 15.0 20.3 56.1 Total revenues $ 394.3 $ 193.2 $ 149.7 $ 328.9 $ 224.8 $ 15.0 $ 20.3 $ 1,326.2 Revenue by contract duration was as follows: Successor Three Months Ended March 31, 2018 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Long-term contracts $ 211.8 $ 106.4 $ 117.7 $ 7.6 $ 44.6 $ — $ — $ 488.1 Short-term contracts 131.6 81.2 9.6 389.9 132.7 — — 745.0 Spot 45.8 14.0 11.0 67.8 23.7 — — 162.3 Other 0.1 0.1 5.4 0.9 0.4 20.1 40.3 67.3 Total revenues $ 389.3 $ 201.7 $ 143.7 $ 466.2 $ 201.4 $ 20.1 $ 40.3 $ 1,462.7 Predecessor Three Months Ended March 31, 2017 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Long-term contracts $ 238.5 $ 130.0 $ 119.4 $ 4.9 $ 33.4 $ — $ — $ 526.2 Short-term contracts 119.2 63.2 9.9 235.7 100.7 — — 528.7 Spot 36.6 — 4.2 84.0 90.4 — — 215.2 Other — — 16.2 4.3 0.3 15.0 20.3 56.1 Total revenues $ 394.3 $ 193.2 $ 149.7 $ 328.9 $ 224.8 $ 15.0 $ 20.3 $ 1,326.2 Committed Revenue From Contracts With Customers The Company expects to recognize revenue subsequent to March 31, 2018 of approximately $6.0 billion related to contracts with customers in which volumes and prices per ton were fixed or reasonably estimable at March 31, 2018 . Approximately 50% of such amount is expected to be recognized over the next twelve months and the remainder thereafter. Actual revenue related to such contracts may differ materially for various reasons, including price adjustment features for coal quality and cost escalations, volume optionality provisions and potential force majeure events. This estimate of future revenue does not include any revenue related to contracts with variable prices per ton that cannot be reasonably estimated, such as the majority of Australian metallurgical and seaborne thermal coal contracts where pricing is negotiated or settled quarterly or annually.

Discontinued Operations

Discontinued Operations	3 Months Ended
	Mar. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations Discontinued operations include certain former Australian Thermal Mining and Midwestern U.S. Mining segment assets that have ceased production and other previously divested legacy operations, including Patriot Coal Corporation and certain of its wholly-owned subsidiaries (Patriot). Summarized Results of Discontinued Operations Results from discontinued operations were as follows during the periods presented below: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Loss from discontinued operations, net of income taxes $ (1.3 ) $ (4.1 ) Assets and Liabilities of Discontinued Operations Assets and liabilities classified as discontinued operations included in the Company’s condensed consolidated balance sheets were as follows: March 31, 2018 December 31, 2017 (Dollars in millions) Assets: Other current assets $ 0.6 $ 0.3 Total assets classified as discontinued operations $ 0.6 $ 0.3 Liabilities: Accounts payable and accrued expenses $ 70.7 $ 70.6 Other noncurrent liabilities 170.6 170.0 Total liabilities classified as discontinued operations $ 241.3 $ 240.6 Patriot-Related Matters A significant portion of the liabilities in the table above relate to a former subsidiary, Patriot Coal Corporation. In 2012, Patriot filed voluntary petitions for relief under Chapter 11 of Title 11 of the U.S. Code. In 2013, the Company entered into a definitive settlement agreement (2013 Agreement) with Patriot and the United Mine Workers of America (UMWA), on behalf of itself, its represented Patriot employees and its represented Patriot retirees, to resolve all then disputed issues related to Patriot’s bankruptcy. In May 2015, Patriot again filed voluntary petitions for relief under Chapter 11 of Title 11 of the U.S. Code in the Eastern District of Virginia and subsequently initiated a process to sell some or all of its assets to qualified bidders. On October 9, 2015, Patriot’s bankruptcy court entered an order confirming Patriot’s plan of reorganization, which provided, among other things, for the sale of substantially all of Patriot’s assets to two different buyers. Black Lung Occupational Disease Liabilities. Patriot had federal and state black lung occupational disease liabilities related to workers employed in periods prior to Patriot’s spin-off from the Company in 2007. Upon spin-off, Patriot indemnified the Company against any claim relating to these liabilities, which amounted to approximately $150 million at that time. The indemnification included any claim made by the U.S. Department of Labor (DOL) against the Company with respect to these obligations as a potentially liable operator under the Federal Coal Mine Health and Safety Act of 1969. The 2013 Agreement included Patriot’s affirmance of indemnities provided in the spin-off agreements, including the indemnity relating to such black lung liabilities; however, Patriot rejected this indemnity in its May 2015 bankruptcy. By statute, the Company had secondary liability for the black lung liabilities related to Patriot’s workers employed by former subsidiaries of the Company. Whether the Company will ultimately be required to fund certain of those obligations in the future as a result of Patriot’s May 2015 bankruptcy remains uncertain. The amount of the liability was $134.9 million at March 31, 2018 , which was determined on an actuarial basis based on the best information available to the Company. While the Company has recorded a liability, it intends to review each claim on a case-by-case basis and contest liability estimates as appropriate. The amount of the Company’s recorded liability reflects only Patriot workers employed by former subsidiaries of the Company that are presently retired, disabled or otherwise not actively employed. The Company cannot reliably estimate the potential liabilities for Patriot’s workers employed by former subsidiaries of the Company that are presently active in the workforce because of the potential for such workers to continue to work for another coal operator that is a going concern. The Company’s accounting for the black lung liabilities related to Patriot is based on an interpretation of applicable statutes. Management believes that inconsistencies exist among the applicable statutes, regulations promulgated under those statutes and the DOL’s interpretative guidance. The Company may seek clarification from the DOL regarding these inconsistencies and the accounting for these liabilities could be reduced in the future depending on the DOL’s responses to inquiries. UMWA 1974 Pension Plan (UMWA Plan) Litigation. On July 16, 2015, a lawsuit was filed by the UMWA Plan, the UMWA 1974 Pension Trust (Trust) and the Trustees of the UMWA Plan and Trust (Trustees) in the United States District Court for the District of Columbia, against PEC, Peabody Holding Company, LLC, a subsidiary of the Company, and Arch Coal, Inc. The plaintiffs sought, pursuant to the Employee Retirement Income Security Act of 1974 (ERISA) and the Multiemployer Pension Plan Amendments Act of 1980, a declaratory judgment that the defendants were obligated to arbitrate any opposition to the Trustees’ determination that the defendants have statutory withdrawal liability as a result of the 2015 Patriot bankruptcy. After a legal and arbitration process and with the approval of the Bankruptcy Court, on January 25, 2017, the UMWA Plan and the Debtors agreed to a settlement of the claim whereby the UMWA Plan will be entitled to $75 million to be paid by the Company in increments through 2021. The balance of the liability, on a discounted basis, was $47.4 million at March 31, 2018 .

Inventories

Inventories	3 Months Ended
	Mar. 31, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories as of March 31, 2018 and December 31, 2017 consisted of the following: March 31, 2018 December 31, 2017 (Dollars in millions) Materials and supplies $ 103.1 $ 101.5 Raw coal 56.6 78.1 Saleable coal 105.8 111.7 Total $ 265.5 $ 291.3 Materials and supplies inventories presented above have been shown net of reserves of $0.5 million and $0.6 million as of March 31, 2018 and December 31, 2017 , respectively.

Derivatives and Fair Value Meas

Derivatives and Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Derivatives and Fair Value Measurements	Derivatives and Fair Value Measurements Risk Management — Corporate Hedging Activities The Company is exposed to several risks in the normal course of business, including (1) foreign currency exchange rate risk for non-U.S. dollar expenditures and balances, (2) price risk on coal produced by and diesel fuel utilized in the Company’s mining operations and (3) interest rate risk that has been partially mitigated by fixed rates on long-term debt. The Company manages a portion of its price risk related to the sale of coal (excluding coal trading activities) using long-term coal supply agreements, rather than using derivative instruments. Derivative financial instruments have historically been used to manage the Company’s risk exposure to foreign currency exchange rate risk, primarily on Australian dollar expenditures made in its Australian mining platform. This risk was historically managed using forward contracts and options designated as cash flow hedges, with the objective of reducing the variability of cash flows associated with forecasted foreign currency expenditures. The Company has also used derivative instruments to manage its exposure to the variability of diesel fuel prices used in production in the U.S. and Australia with swaps or options, which it has also designated as cash flow hedges, with the objective of reducing the variability of cash flows associated with forecasted diesel fuel purchases. These risk management activities are collectively referred to as “Corporate Hedging” and are actively monitored for compliance with the Company’s risk management policies. The Company had no diesel fuel derivatives in place as of March 31, 2018 or December 31, 2017 . As of March 31, 2018 , the Company had currency options outstanding with an aggregate notional amount of $1,125.0 million Australian dollars to hedge currency risk associated with anticipated Australian dollar expenditures during the remainder of 2018. The instruments are quarterly average rate options whereby the Company is entitled to receive payment on the notional amount should the quarterly average Australian dollar-to-U.S. dollar exchange rate exceed amounts ranging from $0.8150 to $0.82 over the remainder of 2018. The currency options are not expected to receive cash flow hedge accounting treatment and changes in fair value will be reflected in current earnings. The currency options’ fair value of $2.3 million and $4.2 million was included in “Other current assets” in the accompanying condensed consolidated balance sheets as of March 31, 2018 and December 31, 2017 , respectively. The tables below show the classification and amounts of pre-tax gains and losses related to the Company’s Corporate Hedging derivatives: Successor Three Months Ended March 31, 2018 Financial Instrument Income Statement Classification of Losses Total loss recognized in income Loss realized in income on derivatives Unrealized loss recognized in income on non-designated derivatives (Dollars in millions) Foreign currency option contracts Operating costs and expenses $ (4.2 ) $ (2.4 ) $ (1.8 ) Total $ (4.2 ) $ (2.4 ) $ (1.8 ) Predecessor Three Months Ended March 31, 2017 Financial Instrument Income Statement Classification of Losses Total loss recognized in income Loss reclassified from other comprehensive loss into income (Dollars in millions) Commodity swap contracts Operating costs and expenses $ (11.0 ) $ (11.0 ) Foreign currency forward contracts Operating costs and expenses (16.6 ) (16.6 ) Total $ (27.6 ) $ (27.6 ) Cash Flow Presentation. The Company classifies the cash effects of its Corporate Hedging derivatives within the “Cash Flows From Operating Activities” section of the accompanying unaudited condensed consolidated statements of cash flows. Fair Value Measurements The Company uses a three-level fair value hierarchy that categorizes assets and liabilities measured at fair value based on the observability of the inputs utilized in the valuation. These levels include: Level 1 - inputs are quoted prices in active markets for the identical assets or liabilities; Level 2 - inputs are other than quoted prices included in Level 1 that are directly or indirectly observable through market-corroborated inputs; and Level 3 - inputs are unobservable, or observable but cannot be market-corroborated, requiring the Company to make assumptions about pricing by market participants. Financial Instruments Measured on a Recurring Basis. The following tables set forth the hierarchy of the Company’s net financial asset positions for which fair value is measured on a recurring basis: March 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Foreign currency contracts $ — $ 2.3 $ — $ 2.3 Total net financial assets $ — $ 2.3 $ — $ 2.3 December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in millions) Foreign currency contracts $ — $ 4.2 $ — $ 4.2 Total net financial assets $ — $ 4.2 $ — $ 4.2 For Level 1 and 2 financial assets and liabilities, the Company utilizes both direct and indirect observable price quotes, including interest rate yield curves, exchange indices, broker/dealer quotes, published indices, issuer spreads, benchmark securities and other market quotes. In the case of certain debt securities, fair value is provided by a third-party pricing service. Below is a summary of the Company’s valuation techniques for Level 1 and 2 financial assets and liabilities: • Foreign currency forward and option contracts: valued utilizing inputs obtained in quoted public markets (Level 2) except when credit and non-performance risk is considered to be a significant input, then the Company classifies such contracts as Level 3. Other Financial Instruments. The Company used the following methods and assumptions in estimating fair values for other financial instruments as of March 31, 2018 and December 31, 2017 : • Cash and cash equivalents, restricted cash, accounts receivable, including those within the Company’s accounts receivable securitization program, notes receivable and accounts payable have carrying values which approximate fair value due to the short maturity or the liquid nature of these instruments. • Long-term debt fair value estimates are based on observed prices for securities with an active trading market when available (Level 2), and otherwise on estimated borrowing rates to discount the cash flows to their present value (Level 3). The carrying amounts and estimated fair values of the Company’s current and long-term debt as of March 31, 2018 and December 31, 2017 are summarized as follows: March 31, 2018 December 31, 2017 Carrying Estimated Carrying Estimated (Dollars in millions) Current and Long-term debt $ 1,455.2 $ 1,535.6 $ 1,460.8 $ 1,547.4 The Company had no transfers between fair value hierarchy levels for either financial instruments measured on a recurring basis or other financial instruments during the three months ended March 31, 2018 and 2017 . The Company’s policy is to value all transfers between levels using the beginning of period valuation.

Coal Trading

Coal Trading	3 Months Ended
	Mar. 31, 2018
Coal Trading [Abstract]
Coal Trading	Coal Trading The Company engages in the direct and brokered trading of coal and freight-related contracts (coal trading). Except those contracts for which the Company has elected to apply a normal purchases and normal sales exception, all derivative coal trading contracts are accounted for at fair value. Coal brokering is conducted both as principal and agent in support of various coal production-related activities that may involve coal produced from the Company's mines, coal sourcing arrangements with third-party mining companies or offtake agreements with other coal producers. The Company’s Trading and Brokerage segment also provides transportation-related services, which involve both financial derivative contracts and physical contracts. Collectively, coal and freight-related hedging activities include both economic hedging and, from time to time, cash flow hedging in support of the Company's coal trading strategy. The Company includes instruments associated with coal trading transactions as a part of its trading book. Trading revenues from such transactions are recorded in “Other revenues” in the unaudited condensed consolidated statements of operations and include realized and unrealized gains and losses on derivative instruments, including those that arise from coal deliveries related to contracts accounted for on an accrual basis under the normal purchases and normal sales exception. Therefore, the Company has elected the trading exemption surrounding disclosure of its coal trading activities. Trading revenues (losses) recognized during the periods presented below were as follows: Successor Predecessor Trading Revenues by Type of Instrument Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Futures, swaps and options $ (16.9 ) $ (10.2 ) Physical purchase/sale contracts 37.0 25.2 Total trading revenues $ 20.1 $ 15.0 Offsetting and Balance Sheet Presentation The Company’s coal trading assets and liabilities include financial instruments, such as swaps, futures and options, cleared through various exchanges, which involve the daily net settlement of open positions. The Company must post cash collateral in the form of initial margin, in addition to variation margin, on exchange-cleared positions that are in a net liability position and receives variation margin when in a net asset position. The Company also transacts in coal trading financial swaps and options through over-the-counter (OTC) markets with financial institutions and other non-financial trading entities under International Swaps and Derivatives Association Master Agreements, which contain symmetrical default provisions. Certain of the Company’s coal trading agreements with OTC counterparties also contain credit support provisions that may periodically require the Company to post, or entitle the Company to receive, variation margin. Physical coal and freight-related purchase and sale contracts included in the Company’s coal trading assets and liabilities are executed pursuant to master purchase and sale agreements that also contain symmetrical default provisions and allow for the netting and setoff of receivables and payables that arise during the same time period. The Company offsets its coal trading asset and liability derivative positions, and variation margin related to those positions, on a counterparty-by-counterparty basis in the condensed consolidated balance sheets, with the fair values of those respective derivatives reflected in “Assets from coal trading activities, net” and “Liabilities from coal trading activities, net.” The fair value of assets and liabilities from coal trading activities presented on a gross and net basis as of March 31, 2018 and December 31, 2017 is set forth below: Affected Line Item in the Condensed Consolidated Balance Sheets Gross Amounts of Recognized Assets (Liabilities) Gross Amounts Offset in the Condensed Consolidated Balance Sheets Variation Margin Posted (1) Net Amounts of Assets (Liabilities) Presented in the Condensed Consolidated Balance Sheets (Dollars in millions) Fair Value as of March 31, 2018 Assets from coal trading activities, net $ 53.6 $ (42.4 ) $ — $ 11.2 Liabilities from coal trading activities, net (57.9 ) 42.4 6.7 (8.8 ) Total, net $ (4.3 ) $ — $ 6.7 $ 2.4 Fair Value as of December 31, 2017 Assets from coal trading activities, net $ 77.1 $ (74.5 ) $ — $ 2.6 Liabilities from coal trading activities, net (122.0 ) 74.5 35.8 (11.7 ) Total, net $ (44.9 ) $ — $ 35.8 $ (9.1 ) (1) None of the net variation margin posted at March 31, 2018 and December 31, 2017 related to cash flow hedges. Fair Value Measurements The following tables set forth the hierarchy of the Company’s net financial asset (liability) coal trading positions for which fair value is measured on a recurring basis as of March 31, 2018 and December 31, 2017 : March 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Futures, swaps and options $ 0.2 $ — $ — $ 0.2 Physical purchase/sale contracts — 2.2 — 2.2 Total net financial assets $ 0.2 $ 2.2 $ — $ 2.4 December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in millions) Futures, swaps and options $ (3.0 ) $ (4.2 ) $ — $ (7.2 ) Physical purchase/sale contracts — (1.9 ) — (1.9 ) Total net financial liabilities $ (3.0 ) $ (6.1 ) $ — $ (9.1 ) For Level 1 and 2 financial assets and liabilities, the Company utilizes both direct and indirect observable price quotes, including U.S. interest rate curves; LIBOR yield curves; Chicago Mercantile Exchange Group, Intercontinental Exchange, Baltic Exchange and Singapore Exchange contract prices; broker quotes; published indices; and other market quotes. Below is a summary of the Company’s valuation techniques for Level 1 and 2 financial assets and liabilities: • Futures, swaps and options: generally valued based on unadjusted quoted prices in active markets (Level 1) or a valuation that is corroborated by the use of market-based pricing (Level 2) except when credit and non-performance risk is considered to be a significant input (greater than 10% of fair value), then the Company classifies as Level 3. • Physical purchase/sale contracts: purchases and sales at locations with significant market activity corroborated by market-based information (Level 2) except when credit and non-performance risk is considered to be a significant input (greater than 10% of fair value), then the Company classifies as Level 3. As of March 31, 2018 , the timing of the estimated future realization of the value of the Company’s trading portfolio was as follows: Percentage of Year of Expiration Portfolio Total 2018 83 % 2019 25 % 2020 (8 )% 100 % Credit and Non-performance Risk. The fair value of the Company’s coal derivative assets and liabilities reflects adjustments for credit risk. The Company’s exposure is substantially with electric utilities, energy marketers, steel producers and nonfinancial trading houses. The Company’s policy is to independently evaluate each customer’s creditworthiness prior to entering into transactions and to regularly monitor the credit extended. If the Company engages in a transaction with a counterparty that does not meet its credit standards, the Company seeks to protect its position by requiring the counterparty to provide an appropriate credit enhancement. Also, when appropriate (as determined by its credit management function), the Company has taken steps to reduce its exposure to customers or counterparties whose credit has deteriorated and who may pose a higher risk of failure to perform under their contractual obligations. These steps include obtaining letters of credit or cash collateral (margin), requiring prepayments for shipments or the creation of customer trust accounts held for the Company’s benefit to serve as collateral in the event of a failure to pay or perform. To reduce its credit exposure related to trading and brokerage activities, the Company seeks to enter into netting agreements with counterparties that permit the Company to offset asset and liability positions with such counterparties and, to the extent required, the Company will post or receive margin amounts associated with exchange-cleared and certain OTC positions. The Company also continually monitors counterparty and contract non-performance risk, if present, on a case-by-case basis. At March 31, 2018 , 55% of the Company’s credit exposure related to coal trading activities was with investment grade counterparties, while 1% was with non-investment grade counterparties and 44% was with counterparties that are not rated. Performance Assurances and Collateral The Company is required to post variation margin on positions that are in a net liability position and is entitled to receive and hold variation margin on positions that are in a net asset position with an exchange and certain of its OTC derivative contract counterparties. At March 31, 2018 and December 31, 2017 , the Company posted a net variation margin of $6.7 million and $35.8 million , respectively. In addition to the requirements surrounding variation margin, the Company is required by the exchanges upon which it transacts to post certain additional collateral, known as initial margin, which represents an estimate of potential future adverse price movements across the Company’s portfolio under normal market conditions. The Company posted initial margin of $18.5 million as of March 31, 2018 , compared to $18.8 million as of December 31, 2017 , which is reflected in “Other current assets” in the condensed consolidated balance sheets. As of March 31, 2018 and December 31, 2017, the Company was in receipt of $4.6 million and $1.8 million , respectively, of the required variation and initial margin. Certain of the Company’s derivative trading instruments require the parties to provide additional performance assurances whenever a material adverse event jeopardizes one party’s ability to perform under the instrument. If the Company was to sustain a material adverse event (using commercially reasonable standards), its counterparties could request collateralization on derivative trading instruments in net liability positions which, based on an aggregate fair value at March 31, 2018 and December 31, 2017 , would have amounted to collateral postings to counterparties of approximately $1.1 million and $7.0 million , respectively. As of March 31, 2018 , the Company was not required to post collateral, whereas on December 31, 2017 , the Company was required to post approximately $0.4 million in collateral to counterparties for such positions Certain of the Company’s other derivative trading instruments require the parties to provide additional performance assurances whenever a credit downgrade occurs below a certain level, as specified in each underlying contract. The terms of such derivative trading instruments typically require additional collateralization, which is commensurate with the severity of the credit downgrade. During the first quarter of 2018, one major rating agency upgraded the Company’s corporate credit rating, thus improving the Company’s credit position with its counterparties. The Company’s collateral requirement owed to its counterparties for these ratings based derivative trading instruments for March 31, 2018 remained at zero , consistent with December 31, 2017 . As of March 31, 2018 and December 31, 2017 , no collateral was posted to counterparties to support such derivative trading instruments.

Intangible Contract Assets and

Intangible Contract Assets and Liabilities	3 Months Ended
	Mar. 31, 2018
Revenue Recognition [Abstract]
Intangible Contract Assets and Liabilities	Intangible Contract Assets and Liabilities At the Effective Date, the Company recorded intangible assets of $314.9 million and liabilities of $58.7 million to reflect the inherent fair value of certain U.S. coal supply agreements as a result of favorable and unfavorable differences between contract terms and estimated market terms for the same coal products, and also recorded intangible liabilities of $116.2 million related to unutilized capacity under its port and rail take-or-pay contracts. The balances and respective balance sheet classifications of such assets and liabilities at March 31, 2018 and December 31, 2017 , net of accumulated amortization, are set forth in the following tables: March 31, 2018 (Dollars in millions) Assets Liabilities Net Total Coal supply agreements $ 143.8 $ (38.6 ) $ 105.2 Take-or-pay contracts — (81.1 ) (81.1 ) Total $ 143.8 $ (119.7 ) $ 24.1 Balance sheet classification: Investments and other assets $ 143.8 $ — $ 143.8 Accounts payable and accrued expenses — (25.1 ) (25.1 ) Other noncurrent liabilities — (94.6 ) (94.6 ) Total $ 143.8 $ (119.7 ) $ 24.1 December 31, 2017 (Dollars in millions) Assets Liabilities Net Total Coal supply agreements $ 177.2 $ (42.7 ) $ 134.5 Take-or-pay contracts — (90.7 ) (90.7 ) Total $ 177.2 $ (133.4 ) $ 43.8 Balance sheet classification: Investments and other assets $ 177.2 $ — $ 177.2 Accounts payable and accrued expenses — (27.6 ) (27.6 ) Other noncurrent liabilities — (105.8 ) (105.8 ) Total $ 177.2 $ (133.4 ) $ 43.8 Amortization of the intangible assets and liabilities related to coal supply agreements occurs ratably based upon coal volumes shipped per contract and is recorded as a component of “Depreciation, depletion and amortization” in the accompanying condensed consolidated statements of operations. Such amortization amounted to $29.3 million during the three months ended March 31, 2018 . The Company anticipates net amortization of sales contracts, based upon expected shipments in the next five years, to be an expense of approximately $68 million during the nine months ended December 31, 2018 , and for the years 2019 through 2022 , expense of approximately $27 million , $8 million , $3 million , and $1 million , respectively. Future unutilized capacity and the amortization periods related to the take-or-pay contract intangible liabilities are based upon estimates of forecasted usage. Such amortization, which is classified as a reduction to “Operating costs and expenses” in the accompanying condensed consolidated statements of operations, amounted to $8.3 million during the three months ended March 31, 2018 . The Company anticipates net amortization of take-or-pay contract intangible liabilities to be approximately $19 million during the nine months ended December 31, 2018 , and for the years 2019 through 2022 , approximately $18 million , $9 million , $4 million , and $3 million , respectively.

Equity Method Investments

Equity Method Investments	3 Months Ended
	Mar. 31, 2018
Financing Receivables [Abstract]
Equity Method Investments and Financing Receivables	Equity Method Investments The Company had total equity method investments of $72.3 million and $83.8 million reflected in “Investments and other assets” in the condensed consolidated balance sheets as of March 31, 2018 and December 31, 2017 , respectively, related to Middlemount Coal Pty Ltd (Middlemount). As noted in Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 , the carrying value of the equity method investments and financing receivables was adjusted to fair value in connection with fresh start reporting based on the net present value of future cash flows associated with the Company’s 50% equity interest in Middlemount. The Company received cash payments from Middlemount of $35.8 million and $31.0 million during the three months ended March 31, 2018 and 2017 , respectively.

Property, Plant, Equipment and

Property, Plant, Equipment and Mine Development	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant, Equipment and Mine Development	Property, Plant, Equipment and Mine Development The composition of property, plant, equipment and mine development, net, as of March 31, 2018 and December 31, 2017 is set forth in the table below. Refer to Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 for details regarding the impact of fresh start reporting on property, plant, equipment and mine development. March 31, 2018 December 31, 2017 (Dollars in millions) Land and coal interests $ 3,891.7 $ 3,890.5 Buildings and improvements 452.3 470.6 Machinery and equipment 1,195.1 1,149.3 Less: Accumulated depreciation, depletion and amortization (531.1 ) (398.5 ) Property, plant, equipment and mine development, net $ 5,008.0 $ 5,111.9

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s effective tax rate before remeasurement for the three months ended March 31, 2018 is based on the Company’s estimated full year effective tax rate, comprised of expected statutory tax benefit, offset by foreign rate differential and changes in valuation allowance. The Company’s income tax provision of $10.1 million and $2.2 million for the three months ended March 31, 2018 and 2017 , respectively, included tax provisions of $0.5 million and $9.4 million , respectively, related to the remeasurement of foreign income tax accounts. On December 22, 2017, the Tax Cuts and Jobs Act (the Act) was signed into law making significant changes to the Internal Revenue Code. Certain provisions of the Act applied to taxable years beginning after December 31, 2017 and therefore have an impact on the three months ended March 31, 2018. The Company has determined that a significant portion of the provisions will not have a material impact. The Company is continuing to gather additional information and anticipates completing the analysis for the following item by December 31, 2018: • Global Intangible Low-Taxed Income (GILTI): The Act subjects a U.S. shareholder to current tax on GILTI of its controlled foreign corporations (CFCs) for taxable years beginning after December 31, 2017. GILTI is calculated as the excess of a U.S. shareholder’s pro-rata share of net income of CFCs over a calculated return on specific tangible assets of the CFCs. The GILTI will be offset by net operating losses in the U.S. and a corresponding valuation allowance release and will not impact the effective tax rate. The Company has elected to account for GILTI as a period charge in the period the tax arises. The Company has not completed its assessment for the income tax effects of the Act related to the repeal of the corporate alternative minimum tax system, remeasurement of deferred tax assets and liabilities and elimination of executive compensation exemptions. However, as noted in Note 11. “Income Taxes” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017, the Company was able to reasonably estimate certain effects for these items and therefore recorded provisional adjustments. The Company has not made any additional measurement-period adjustments related to these items during the three months ended March 31, 2018. The Company is continuing to gather additional information and anticipates completing the analysis for these items by December 22, 2018, within the one-year measurement period.

Long-term Debt

Long-term Debt	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Long-term Debt	Long-term Debt In accordance with the Plan, the Company was recapitalized with new debt and equity instruments, including the 6.000% Senior Secured Notes due March 2022, the 6.375% Senior Secured Notes due March 2025, and the Senior Secured Term Loan due 2025 in the table below. The Company’s total indebtedness as of March 31, 2018 and December 31, 2017 consisted of the following: March 31, 2018 December 31, 2017 (Dollars in millions) 6.000% Senior Secured Notes due March 2022 $ 500.0 $ 500.0 6.375% Senior Secured Notes due March 2025 500.0 500.0 Senior Secured Term Loan due 2025 444.3 444.2 Capital lease and other obligations 67.8 76.0 Less: Debt issuance costs (56.9 ) (59.4 ) 1,455.2 1,460.8 Less: Current portion of long-term debt 87.1 42.1 Long-term debt $ 1,368.1 $ 1,418.7 In connection with the Chapter 11 Cases, the Company was required to pay adequate protection payments of $29.8 million to certain first lien creditors of the Predecessor company during the three months ended March 31, 2017. The adequate protection payments were recorded as “Interest expense” in the unaudited condensed consolidated statements of operations and ceased upon the Effective Date. The Company did not record interest expense subsequent to the filing of the Bankruptcy Petitions for the majority non-first lien Predecessor indebtedness, which was automatically stayed in accordance with Section 502(b)(2) of the Bankruptcy Code. The amount of contractual interest stayed was $92.9 million for the period January 1, 2017 through the Effective Date. 6.000% and 6.375% Senior Secured Notes On February 15, 2017, one of PEC’s subsidiaries entered into an indenture (the Indenture) with Wilmington Trust, National Association, as trustee, relating to the issuance by PEC’s subsidiary of $500.0 million aggregate principal amount of 6.000% senior secured notes due 2022 (the 2022 Notes) and $500.0 million aggregate principal amount of 6.375% senior secured notes due 2025 (the 2025 Notes and, together with the 2022 Notes, the Senior Notes). The Senior Notes were sold on February 15, 2017 in a private transaction exempt from the registration requirements of the Securities Act of 1933. The proceeds from the Senior Notes were used to repay the Predecessor company first lien obligations. The Senior Notes were issued at par value. The Company paid aggregate debt issuance costs of $49.5 million related to the offering, which will be amortized over the respective terms of the Senior Notes. Interest payments on the Senior Notes are scheduled to occur each year on March 31st and September 30th until maturity. During the three months ended March 31, 2018 , the Company recorded interest expense of $17.5 million related to the Senior Notes. The Company may redeem the 2022 Notes, in whole or in part, beginning in 2019 at 103.0% of par, in 2020 at 101.5% of par, and in 2021 and thereafter at par. The 2025 Notes may be redeemed, in whole or in part, beginning in 2020 at 104.8% of par, in 2021 at 103.2% of par, in 2022 at 101.6% of par, and in 2023 and thereafter at par. In addition, prior to the first date on which the Senior Notes are redeemable at the redemption prices noted above, the Company may also redeem some or all of the Senior Notes at a calculated make-whole premium, plus accrued and unpaid interest. The Indenture contains customary conditions of default and imposes certain restrictions on the Company’s activities, including its ability to incur liens, incur debt, make investments, engage in fundamental changes such as mergers and dissolutions, dispose of assets, enter into transactions with affiliates, and make certain restricted payments, such as cash dividends and share repurchases. The Senior Notes rank senior in right of payment to any subordinated indebtedness and equally in right of payment with any senior indebtedness to the extent of the collateral securing that indebtedness. The Senior Notes are jointly and severally and fully and unconditionally guaranteed on a senior secured basis by substantially all of the Company’s material domestic subsidiaries and secured by first priority liens over (1) substantially all of the assets of the Company and the guarantors, except for certain excluded assets, (2) 100% of the capital stock of each domestic restricted subsidiary of the Company, (3) 100% of the non-voting capital stock of each first tier foreign subsidiary of the Company or a foreign subsidiary holding company and no more than 65% of the voting capital stock of each first tier foreign subsidiary of the Company or a foreign subsidiary holding company, (4) a legal charge of 65% of the voting capital stock and 100% of the non-voting capital stock of Peabody Investments (Gibraltar) Limited and (5) all intercompany debt owed to the Company or any guarantor, in each case, subject to certain exceptions. The obligations under the Senior Notes are secured on a pari passu basis by the same collateral securing the Credit Agreement (as defined below), subject to certain exceptions. Credit Agreement In connection with an exit facility commitment letter, on the Effective Date, the Company entered into a credit agreement, dated as of April 3, 2017, among the Company, as Borrower, Goldman Sachs Bank USA, as Administrative Agent, and other lenders party thereto (the Credit Agreement). The Credit Agreement originally provided for a $950.0 million senior secured term loan (the Senior Secured Term Loan), which was to mature in 2022 prior to the amendments described below. The proceeds from the Senior Secured Term Loan were used to repay the Predecessor company first lien obligations. Following the voluntary prepayments described below, the Credit Agreement provided for a $450.0 million first lien senior secured term loan, which bore interest at LIBOR plus 3.50% per annum with a 1.00% LIBOR floor as of March 31, 2018 . During the three months ended March 31, 2018 , the Company recorded interest expense of $6.6 million related to the Senior Secured Term Loan. Proceeds from the Senior Secured Term Loan were received net of an original issue discount and deferred financing costs of $37.3 million that will be amortized over its term. The loan principal is payable in quarterly installments plus accrued interest through December 2024 with the remaining balance due in March 2025. The loan principal is voluntarily prepayable at 101% of the principal amount repaid if voluntarily prepaid prior to October 2018 (subject to certain exceptions, including prepayments made with internally generated cash) and is voluntarily prepayable at any time thereafter without premium or penalty. The Senior Secured Term Loan may require mandatory principal prepayments of 75% of Excess Cash Flow (as defined in the Credit Agreement) for any fiscal year (commencing with the fiscal year ending December 31, 2018). The mandatory principal prepayment requirement changes to (i) 50% of Excess Cash Flow if the Company’s Total Leverage Ratio (as defined in the Credit Agreement and calculated as of December 31) is less than or equal to 2.00 :1.00 and greater than 1.50 :1.00, (ii) 25% of Excess Cash Flow if the Company’s Total Leverage Ratio is less than or equal to 1.50 :1.00 and greater than 1.00 :1.00, or (iii) zero if the Company’s Total Leverage Ratio is less than or equal to 1.00 :1.00. If required, mandatory prepayments resulting from Excess Cash Flows are payable within 100 days after the end of each fiscal year. In certain circumstances, the Senior Secured Term Loan also requires that Excess Proceeds (as defined in the Credit Agreement) of $10.0 million or greater from sales of Company assets be applied against the loan principal, unless such proceeds are reinvested within one year. The Credit Agreement contains customary conditions of default and imposes certain restrictions on the Company’s activities, including its ability to incur liens, incur debt, make investments, engage in fundamental changes such as mergers and dissolutions, dispose of assets, enter into transactions with affiliates, and make certain restricted payments, such as cash dividends and share repurchases. Obligations under the Credit Agreement are secured on a pari passu basis by the same collateral securing the Senior Notes. The Company voluntarily prepaid $500.0 million of the original $950.0 million loan principal amount on the Senior Secured Term Loan in $150.0 million installments on July 31, 2017 and September 11, 2017 and a $200.0 million installment on December 29, 2017. On September 18, 2017, the Company entered into an amendment to the Credit Agreement which lowered the interest rate from LIBOR plus 4.50% per annum with a 1.00% LIBOR floor to LIBOR plus 3.50% per annum with a 1.00% LIBOR floor. The amendment permitted the Company to add an incremental revolving credit facility in addition to the Company’s ability to add one or more incremental term loan facilities under the Credit Agreement. The incremental revolving credit facility and/or incremental term loan facilities can be in an aggregate principal amount of up to $350.0 million plus additional amounts so long as the Company is below Total Leverage Ratio requirements as set forth in the Credit Agreement. The amendment also made available an additional restricted payment basket that permits additional repurchases, dividends or other distributions with respect to the Company’s Common and Preferred Stock in an aggregate amount up to $450.0 million so long as the Company’s Fixed Charge Coverage Ratio (as defined in the Credit Agreement) would not exceed 2.00 :1.00 on a pro forma basis. During the fourth quarter of 2017, the Company entered into the incremental revolving credit facility (the Revolver) for an aggregate commitment of $350.0 million for general corporate purposes. The Company paid aggregate debt issuance costs of $4.7 million . The Revolver matures in November 2020 and permits loans which bear interest at LIBOR plus 3.25% . The Revolver is subject to a 2.00 :1.00 Total Leverage Ratio requirement, modified to limit unrestricted cash netting to $800.0 million . Capacity under the Revolver may also be utilized for letters of credit which incur combined fees of 3.375% per annum. Unused capacity under the Revolver bears a commitment fee of 0.5% per annum. As of March 31, 2018, the Revolver has only been utilized for letters of credit amounting to $163.1 million . Such letters of credit were primarily in support of the Company’s reclamation obligations, as further described in Note 17. “Financial Instruments and Other Guarantees.” During the three months ended March 31, 2018 , the Company recorded interest expense and fees of $1.8 million related to the Revolver. On April 11, 2018, the Company entered into another amendment to the Credit Agreement which further lowered the interest rate on the Senior Secured Term Loan to LIBOR plus 2.75% and eliminated the LIBOR floor. The amendment also extends the maturity of the Senior Secured Term Loan by three years to 2025 and eliminates previous capital expenditure restriction covenants on both the Senior Secured Term Loan and the Revolver. In connection with this amendment, the Company incurred customary fees of approximately $2.0 million and repaid additional principal of $46.0 million which is reflected within “Current portion of long-term debt” in the accompany condensed consolidated balance sheets at March 31, 2018. Restricted Payments Under the Senior Notes and Credit Agreement In addition to the $450.0 million restricted payment basket provided for under the September 18, 2017 amendment, the Credit Agreement provides a builder basket for additional restricted payments subject to a maximum Total Leverage Ratio of 2.00 :1.00 (as defined in the Credit Agreement). The Indenture provides a builder basket for restricted payments that is calculated based upon the Company’s Consolidated Net Income, and is subject to a Fixed Charge Coverage Ratio of at least 2.25 :1.00 (as defined in the Indenture). Under both the Indenture and Credit Agreement, additional restricted payments are permitted through a $50.0 million general basket and an annual aggregate $25.0 million basket which allows dividends and Common Stock repurchases. The payment of dividends and purchases of Common Stock under this latter basket are permitted so long as the Company’s Total Leverage Ratio would not exceed 1.25 :1.00 on a pro forma basis (as defined in the Credit Agreement and Indenture). Copies of the Indenture documents are incorporated as Exhibit 4.3 to the Current Report on Form 8-K filed by the Company with the SEC on April 3, 2017. A copy of the Credit Agreement is included as Exhibit 10.3 to the Current Report on Form 8-K filed by the Company with the SEC on April 3, 2017, and copies of the subsequent amendments are included as Exhibit 10.1 to the Current Reports on Form 8-K filed by the Company with the SEC on September 18, 2017, November 20, 2017, December 19, 2017 and April 11, 2018, respectively.

Pension and Postretirement Bene

Pension and Postretirement Benefit Costs	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Pension and Postretirement Benefit Costs	Pension and Postretirement Benefit Costs The components of net periodic pension and postretirement benefit costs, excluding the service cost for benefits earned, are included in “Net periodic benefit costs, excluding service cost” in the unaudited condensed consolidated statements of operations. Net periodic pension (benefit) cost included the following components: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Service cost for benefits earned $ 0.6 $ 0.6 Interest cost on projected benefit obligation 7.8 9.7 Expected return on plan assets (10.7 ) (11.0 ) Amortization of prior service cost and net actuarial loss — 6.4 Net periodic pension (benefit) cost $ (2.3 ) $ 5.7 Annual contributions to the qualified plans are made in accordance with minimum funding standards and the Company’s agreement with the Pension Benefit Guaranty Corporation. Funding decisions also consider certain funded status thresholds defined by the Pension Protection Act of 2006 (generally 80% ). As of March 31, 2018 , the Company’s qualified plans were expected to be at or above the Pension Protection Act thresholds. Prior to emergence from the Chapter 11 Cases, the Company incurred pension costs for two non-qualified pension plans which it no longer sponsors. Minimum funding standards are legislated by ERISA and are modified by pension funding stabilization provisions included in the Moving Ahead for Progress in the 21st Century Act of 2012, the Highway and Transportation Funding Act of 2014 and the Bipartisan Budget Act of 2015. Based upon minimum funding requirements, the Company is not required to make any contributions to its qualified pension plans in 2018; however, during the three months ended March 31, 2018 , the Company made a discretionary contribution of $30.0 million to one of its qualified pension plans. Net periodic postretirement benefit cost included the following components: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Service cost for benefits earned $ 2.0 $ 2.3 Interest cost on accumulated postretirement benefit obligation 7.1 8.4 Amortization of prior service cost and net actuarial loss — 3.2 Net periodic postretirement benefit cost $ 9.1 $ 13.9

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income The following table sets forth the after-tax components of accumulated other comprehensive income and changes thereto recorded during the three months ended March 31, 2018 : Foreign Currency Translation Adjustment Total Accumulated Other Comprehensive Income (Dollars in millions) December 31, 2017 $ 1.4 $ 1.4 Current period change (0.8 ) (0.8 ) March 31, 2018 $ 0.6 $ 0.6 The components of accumulated other comprehensive income (loss) related to postretirement plans and workers’ compensation obligations and cash flow hedges related to Predecessor periods were eliminated in accordance with fresh start reporting as described in Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 . The following table provides additional information regarding items reclassified out of “Accumulated other comprehensive income (loss)” into earnings during the period presented below: Amount reclassified from accumulated other comprehensive income (loss) (1) Predecessor Details about accumulated other comprehensive income (loss) components Three Months Ended March 31, 2017 Affected line item in the unaudited condensed consolidated statement of operations (Dollars in millions) Net actuarial loss associated with postretirement plans and workers’ compensation obligations: Postretirement health care and life insurance benefits $ (5.5 ) Net periodic benefit costs, excluding service cost Defined benefit pension plans (6.3 ) Net periodic benefit costs, excluding service cost Insignificant items 2.7 (9.1 ) Total before income taxes 3.3 Income tax benefit $ (5.8 ) Total after income taxes Prior service credit associated with postretirement plans: Postretirement health care and life insurance benefits $ 2.3 Net periodic benefit costs, excluding service cost Defined benefit pension plans (0.1 ) Net periodic benefit costs, excluding service cost 2.2 Total before income taxes (0.8 ) Income tax provision $ 1.4 Total after income taxes Cash flow hedges: Foreign currency cash flow hedge contracts $ (16.6 ) Operating costs and expenses Fuel and explosives commodity swaps (11.0 ) Operating costs and expenses Insignificant items (0.1 ) (27.7 ) Total before income taxes 9.1 Income tax benefit $ (18.6 ) Total after income taxes (1) Presented as gains (losses) in the unaudited condensed consolidated statements of operations.

Other Events

Other Events	3 Months Ended
	Mar. 31, 2018
Other Events [Abstract]
Other Events	Other Events Divestitures On February 6, 2018, the Company sold its 50% interest in the Red Mountain Joint Venture (RMJV) with BHP Billiton Mitsui Coal Pty Ltd (BMC) for $20.0 million and recorded a gain of $7.1 million , which is included within “Net gain on disposals” in the accompanying unaudited condensed consolidated statements of operations for the three months ended March 31, 2018. RMJV operates the coal handling and preparation plant utilized by the Company’s Millennium Mine. BMC assumed the reclamation obligations and other commitments associated with the assets of RMJV. The Millennium Mine will have continued usage of the coal handling and preparation plant and the associated rail loading facility until the end of 2019 via a coal washing take-or-pay agreement with BMC. In January 2018, Peabody entered into an agreement to sell its share in certain surplus land assets in Queensland’s Bowen Basin to Pembroke Resources South Pty Ltd for approximately $37.0 million Australian dollars. The necessary approval of the Australian Foreign Investment Review Board to complete the transaction was received on March 29, 2018, satisfying all the conditions precedent to the sale, and the Company recorded a gain of $20.6 million , which is included within “Net gain on disposals” in the accompanying unaudited condensed consolidated statements of operations for the three months ended March 31, 2018. The Company had a 37.5% interest in Dominion Terminal Associates, a partnership that operates a coal export terminal in Newport News, Virginia that exports both metallurgical and thermal coal primarily to Europe and Brazil. On March 31, 2017, the Company completed a sale of its interest in Dominion Terminal Associates to Contura Terminal, LLC and Ashland Terminal, Inc., both of which are partners of the Dominion Terminal Associates. The Company collected $20.5 million in proceeds and recorded $19.7 million of gain on the sale, which was classified in “Net gain on disposals” in the accompanying unaudited condensed consolidated statements of operations during the three months ended March 31, 2017. Asset Impairment As described in Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 , the Company adjusted the book values of its property, plant, equipment and mine development assets to estimated fair value in connection with fresh start reporting. During the three months ended March 31, 2018 , the Company recognized no asset impairment charges. During the three months ended March 31, 2017 , the Company recognized asset impairment charges of $30.5 million related to terminated coal lease contracts in the Midwestern United States.

Earnings per Share (EPS)

Earnings per Share (EPS)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings per Share (EPS)	Earnings per Share (EPS) Basic and diluted EPS are computed using the two-class method, which is an earnings allocation that determines EPS for each class of common stock and participating securities according to dividends declared and participation rights in undistributed earnings. The Company’s convertible preferred stock was considered a participating security because holders were entitled to receive dividends on an if-converted basis. The Predecessor Company’s restricted stock awards were considered participating securities because holders were entitled to receive non-forfeitable dividends during the vesting term. Diluted EPS includes securities that could potentially dilute basic EPS during a reporting period and assumes that participating securities are not executed or converted. As such, the Company includes the share-based compensation awards in its potentially dilutive securities. The calculation of diluted EPS for the Predecessor Company also considered the impact of its Convertible Junior Subordinated Debentures due December 2066 (the Debentures). Dilutive securities are not included in the computation of loss per share when a company reports a net loss from continuing operations as the impact would be anti-dilutive. For all but the performance units, the potentially dilutive impact of the Company’s share-based compensation awards is determined using the treasury stock method. Under the treasury stock method, awards are treated as if they had been exercised with any proceeds used to repurchase common stock at the average market price during the period. Any incremental difference between the assumed number of shares issued and purchased is included in the diluted share computation. For the performance units, their contingent features resulted in an assessment for any potentially dilutive common stock by using the end of the reporting period as if it were the end of the contingency period for all units granted. Up to the time of cancellation, a conversion of the Debentures could have resulted in payment for any conversion value in excess of the principal amount of the Debentures in the Predecessor Company’s common stock. For diluted EPS purposes, potential common stock was calculated based on whether the market price of the Predecessor Company’s common stock at the end of each reporting period was in excess of the conversion price of the Debentures. The effect of the Debentures was excluded from the calculation of diluted EPS for all Predecessor periods presented herein because to do so would have been anti-dilutive for those periods. The computation of diluted EPS excluded aggregate share-based compensation awards of less than 0.1 million and approximately 0.2 million for the three months ended March 31, 2018 and 2017 , respectively, because to do so would have been anti-dilutive for those periods. Because the potential dilutive impact of such share-based compensation awards is calculated under the treasury stock method, anti-dilution generally occurs when the exercise prices or unrecognized compensation cost per share of such awards are higher than the Company’s average stock price during the applicable period. The following illustrates the earnings allocation method utilized in the calculation of basic and diluted EPS. Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (In millions, except per share data) EPS numerator: Income from continuing operations, net of income taxes $ 208.3 $ 124.3 Less: Series A Convertible Preferred Stock dividends 102.5 — Less: Net (loss) income attributable to noncontrolling interests (2.1 ) 4.8 Income from continuing operations attributable to common stockholders, before allocation of earnings to participating securities 107.9 119.5 Less: Earnings allocated to participating securities 6.0 1.1 Income from continuing operations attributable to common stockholders, after allocation of earnings to participating securities (1) 101.9 118.4 Loss from discontinued operations, net of income taxes (1.3 ) (4.1 ) Less: Loss from discontinued operations allocated to participating securities (0.1 ) (0.1 ) Loss from discontinued operations attributable to common stockholders, after allocation of earnings to participating securities (1.2 ) (4.0 ) Net income attributable to common stockholders, after allocation of earnings to participating securities (1) $ 100.7 $ 114.4 EPS denominator: Weighted average shares outstanding — basic 120.9 18.3 Impact of dilutive securities 2.3 0.1 Weighted average shares outstanding — diluted (2) 123.2 18.4 Basic EPS attributable to common stockholders: Income from continuing operations $ 0.84 $ 6.46 Loss from discontinued operations (0.01 ) (0.22 ) Net income attributable to common stockholders $ 0.83 $ 6.24 Diluted EPS attributable to common stockholders: Income from continuing operations $ 0.83 $ 6.44 Loss from discontinued operations (0.01 ) (0.23 ) Net income attributable to common stockholders $ 0.82 $ 6.21 (1) The reallocation adjustment for participating securities to arrive at the numerator to calculate diluted EPS was $0.1 million for the three months ended March 31, 2018 and less than $0.1 million for the three months ended March 31, 2017. (2) The two-class method assumes that participating securities are not exercised or converted. As such, weighted average diluted shares outstanding excluded 8.4 million shares related to the participating securities for the three months ended March 31, 2018 . In accordance with the Plan, each share of the Predecessor Company’s common stock outstanding prior to the Effective Date, including all options and warrants to purchase such stock, were extinguished, canceled and discharged, and each such share, option or warrant has no further force or effect after the Effective Date. Furthermore, all of the Predecessor Company’s equity award agreements under prior incentive plans, and the equity awards granted pursuant thereto, were extinguished, canceled and discharged and have no further force or effect after the Effective Date. As of January 31, 2018, all 30.0 million shares of Preferred Stock issued upon the Effective Date had been converted into 59.3 million shares of common stock, which is inclusive of the shares that had been issued for the payable in-kind preferred stock dividends.

Financial Instruments and Other

Financial Instruments and Other Guarantees	3 Months Ended
	Mar. 31, 2018
Financial Instruments And Guarantees With Off Balance Sheet Risk Disclosure [Abstract]
Financial Instruments and Other Guarantees	Financial Instruments and Other Guarantees In the normal course of business, the Company is a party to guarantees and financial instruments, some of which carry off-balance-sheet risk and are not reflected in the accompanying condensed consolidated balance sheets. Such financial instruments are valued based on the amount of exposure under the instrument and the likelihood of required performance. Reclamation Bonding The Company is required to provide various forms of financial assurance in support of its mining reclamation obligations in the jurisdictions in which it operates. Such requirements are typically established by statute or under mining permits. Historically, such assurances have taken the form of third-party instruments such as surety bonds, bank guarantees, letters of credit, collateral held in restricted accounts, and self-bonding arrangements in the U.S. In connection with its emergence from the Chapter 11 Cases, the Company elected to utilize primarily a portfolio of surety bonds to support its U.S. obligations. At March 31, 2018 , the Company’s asset retirement obligations for its U.S. operations of $469.0 million were supported by surety bonds of $1,074.3 million , as well as letters of credit issued under the Company’s receivables securitization program and Revolver amounting to $174.1 million . At March 31, 2018 , the Company’s asset retirement obligations for its Australia operations of $230.2 million were supported by a combination of $270.1 million of surety bonds and bank guarantees, $99.7 million of collateral arrangements, and $14.4 million of similarly issued letters of credit. Accounts Receivable Securitization As described in Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 , the Company entered into the Sixth Amended and Restated Receivables Purchase Agreement, as amended, dated as of April 3, 2017 (the Receivables Purchase Agreement) to extend the Company’s receivables securitization facility previously in place and expand that facility to include certain receivables from the Company’s Australian operations. The term of the receivables securitization program (Securitization Program) ends on April 3, 2020, subject to certain liquidity requirements and other customary events of default set forth in the Receivables Purchase Agreement. The Securitization Program provides for up to $250.0 million in funding accounted for as a secured borrowing, limited to the availability of eligible receivables, and may be secured by a combination of collateral and the trade receivables underlying the program, from time to time. Funding capacity under the Securitization Program may also be drawn upon for letters of credit in support of other obligations. During 2017, the Company entered into amendments to the Securitization Program to include the receivables of additional Australian operations, reduce the restrictions on the availability of certain eligible receivables, add an additional servicer and reduce program fees. Under the terms of the Securitization Program, the Company contributes the trade receivables of its participating subsidiaries on a revolving basis to P&L Receivables, its wholly-owned, bankruptcy-remote subsidiary, which then sells the receivables to unaffiliated banks. P&L Receivables retains the ability to repurchase the receivables in certain circumstances. The assets and liabilities of P&L Receivables are consolidated with Peabody, and the Securitization Program is treated as a secured borrowing for accounting purposes, but the assets of P&L Receivables will be used first to satisfy the creditors of P&L Receivables, not Peabody’s creditors. The borrowings under the Securitization Program remain outstanding throughout the term of the agreement, subject to the Company maintaining sufficient eligible receivables, by continuing to contribute trade receivables to P&L Receivables, unless an event of default occurs. At March 31, 2018 , the Company had no outstanding borrowings and $176.3 million of letters of credit drawn under the Securitization Program. The letters of credit were primarily in support of portions of the Company’s obligations for reclamation, workers’ compensation and postretirement benefits. The Company had no collateral requirement under the Securitization Program at March 31, 2018 and December 31, 2017 . The Company incurred fees associated with the Securitization Program of $1.3 million during the three months ended March 31, 2018 , which have been recorded as interest expense in the accompanying unaudited condensed consolidated statements of operations. As it relates to the former receivables securitization facility in place prior to the Effective Date, the Company incurred interest expense of $2.0 million during the three months ended March 31, 2017 . Collateral Arrangements and Restricted Cash The Company remits cash to certain regulatory authorities and other third parties as collateral for financial assurances associated with a variety of long-term obligations and commitments surrounding the mining, reclamation and shipping of its production. The Company had $109.1 million and $323.1 million held by third parties related to such obligations at March 31, 2018 and December 31, 2017 , respectively. During the three months ended March 31, 2018 , $214.0 million of such collateral was returned to the Company, and the remainder is expected to be returned within the next twelve months, largely as the result of replacing collateral balances with third-party surety bonding in Australia, which was unavailable to the Company prior to 2018. As such, the collateral balance at March 31, 2018 has been classified as current in the accompanying condensed consolidated balance sheets. The Company also had $40.1 million of restricted cash at December 31, 2017 related to a class of pending unsecured creditors’ claims in connection with the Chapter 11 Cases. The restriction was released on March 22, 2018 after the Debtors satisfied all such claims. Other The Company is the lessee under numerous equipment and property leases. It is common in such commercial lease transactions for the Company, as the lessee, to agree to indemnify the lessor for the value of the property or equipment leased, should the property be damaged or lost during the course of the Company’s operations. The Company expects that losses with respect to leased property, if any, would be covered by insurance (subject to deductibles). The Company and certain of its subsidiaries have guaranteed other subsidiaries’ performance under various lease obligations. Aside from indemnification of the lessor for the value of the property leased, the Company’s maximum potential obligations under its leases are equal to the respective future minimum lease payments, and the Company assumes that no amounts could be recovered from third parties. The Company has provided financial guarantees under certain long-term debt agreements entered into by its subsidiaries and substantially all of the Company’s U.S. subsidiaries provide financial guarantees under long-term debt agreements entered into by the Company. The maximum amounts payable under the Company’s debt agreements are equal to the respective principal and interest payments

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments Unconditional Purchase Obligations As of March 31, 2018 , purchase commitments for capital expenditures were $190.1 million , all of which is obligated within the next three years, with $140.7 million obligated in the next year. There were no other material changes to the Company’s commitments from the information provided in Note 25. “Commitments and Contingencies” to the consolidated financial statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . Contingencies From time to time, the Company or its subsidiaries are involved in legal proceedings arising in the ordinary course of business or related to indemnities or historical operations. The Company believes it has recorded adequate reserves for these liabilities. The Company discusses its significant legal proceedings below, including ongoing proceedings and those that impacted the Company’s results of operations for the periods presented. Litigation Relating to the Chapter 11 Cases Ad Hoc Committee . A group of creditors (the Ad Hoc Committee) that held certain interests in the Company's prepetition indebtedness appealed the Bankruptcy Court's order confirming the Plan. On December 29, 2017, the United States District Court for the Eastern District of Missouri (the District Court) entered an order dismissing the Ad Hoc Committee's appeal, and, in the alternative, affirming the order confirming the Plan. On January 26, 2018, the Ad Hoc Committee appealed the District Court's order to the United States Court of Appeals for the Eighth Circuit (the Eighth Circuit). In its appeal, the Ad Hoc Committee does not ask the Eighth Circuit to reverse the order confirming the Plan. Instead, the Ad Hoc Committee asks the Eighth Circuit to award the Ad Hoc Committee members either unspecified damages or the right to buy an unspecified amount of Company stock at a discount. The Company does not believe the appeal is meritorious and will vigorously defend it. Litigation Relating to Continuing Operations Peabody Monto Coal Pty Ltd, Monto Coal 2 Pty Ltd and Peabody Energy Australia PCI Pty Ltd (PEA-PCI). In October 2007, a statement of claim was delivered to Peabody Monto Coal Pty Ltd, a wholly-owned subsidiary of PEA-PCI, that was then known as Macarthur Coal Limited, and Monto Coal 2 Pty Ltd, an equity accounted investee, from the minority interest holders in the Monto Coal Joint Venture, alleging that Monto Coal 2 Pty Ltd breached the Monto Coal Joint Venture Agreement and Peabody Monto Coal Pty Ltd breached the Monto Coal Management Agreement. Peabody Monto Coal Pty Ltd is the manager of the Monto Coal Joint Venture pursuant to the Management Agreement. Monto Coal 2 Pty Ltd holds a 51% interest in the Monto Coal Joint Venture. The plaintiffs are Sanrus Pty Ltd, Edge Developments Pty Ltd and H&J Enterprises (Qld) Pty Ltd. An additional statement of claim was delivered to PEA-PCI in November 2010 from the same minority interest holders in the Monto Coal Joint Venture, alleging that PEA-PCI induced Monto Coal 2 Pty Ltd and Peabody Monto Coal Pty Ltd to breach the Monto Coal Joint Venture Agreement and the Monto Coal Management Agreement, respectively. The plaintiffs later amended their claim to allege damages for lost opportunities to sell their joint venture interest. These actions, which are pending before the Supreme Court of Queensland, Australia, seek damages from the three defendants collectively of amounts ranging from $15.6 million Australian dollars to $1.8 billion Australian dollars, plus interest and costs. The defendants dispute the claims and are vigorously defending their positions. Orders have been made by the court relating to trial preparation steps, with the steps expected to be completed by the end of 2018. The current court order provides the parties will participate in mediation by the end of August 2018. The court also has indicated that it intends to set this matter for a 14 -16 week trial commencing February or March of 2019. Based on the Company’s evaluation of the issues and their potential impact, the amount of any future loss currently cannot be reasonably estimated. Berenergy Corporation. The Company has been in a legal dispute with Berenergy Corporation (Berenergy) regarding Berenergy’s access to certain of its underground oil deposits beneath the Company’s North Antelope Rochelle Mine and contiguous undisturbed areas. Berenergy contends the Company could be liable to Berenergy for the cost of certain special procedures and equipment required to access the secondary deposits remotely from outside the Company’s mine area, which has been estimated as $13.1 million by Berenergy. The Company believes that any claims related to this matter are without merit and constitute prepetition claims. The Company is currently seeking to resolve the underlying access conflict through the Bureau of Land Management (BLM), and believes that the likelihood of a material loss resulting from the matter is remote. County of San Mateo, County of Marin, City of Imperial Beach. The Company was named as a defendant, along with numerous other companies, in three nearly identical lawsuits. The lawsuits seek to hold a wide variety of companies that produce fossil fuels liable for the alleged impacts of the greenhouse gas emissions attributable to those fuels. The lawsuits primarily assert that the companies’ products have caused a sea level rise that is damaging the plaintiffs. The complaints specifically alleged that the defendants’ activities from 1965 to 2015 caused such damage. The Company filed a motion to enforce the Confirmation Order in the Bankruptcy Court because the Confirmation Order enjoins claims that arose before the effective date of the Plan. The motion to enforce was heard on October 5, 2017 and granted on October 24, 2017. The Bankruptcy Court ordered the plaintiffs to dismiss their lawsuits against the Company. On November 26, 2017, the plaintiffs appealed the Bankruptcy Court’s October 24, 2017 order to the U.S. District Court for the Eastern District of Missouri. On November 28, 2017, plaintiffs sought a stay pending appeal from the Bankruptcy Court, which was denied December 8, 2017. On December 19, 2017, the plaintiffs moved the U.S. District Court for the Eastern District of Missouri for a stay pending appeal. No decision from the District Court has been made on the request for a stay and the briefing on the appeal has been completed. The parties are waiting for a decision on the motion for stay and on the merits of the appeal. In the underlying cases pending in California, the District Court for the Northern District of California granted plaintiffs’ motion for remand and decided the cases should be heard in state court. The defendants appealed the order granting remand to the Ninth Circuit and sought a stay of the District Court decision pending completion of the Ninth Circuit appeal. The District Court for the Northern District of California granted defendants’ request for a stay pending completion of the Ninth Circuit appeal. 10th Circuit U.S. Bureau of Land Management Appeal. On September 15, 2017, the Tenth Circuit Court of Appeals reversed the District Court of Wyoming’s decision upholding BLM’s approval of four coal leases in the Powder River Basin. Two of the four leases relate to the Company’s North Antelope Rochelle Mine in Wyoming. There is no immediate impact on the Company’s leases as the Court of Appeals did not vacate the leases as part of its ruling. Rather, the Court of Appeals remanded the case back to the District Court with directions to order BLM to revise its environmental analysis. On November 27, 2017, the District Court ordered BLM to revise its environmental analysis. Plaintiffs then asked the court to order remedy briefing, which defendants and intervenors opposed because the District Court already addressed the proper remedy in its November 27, 2017 order. On April 2, 2018 the federal respondents filed a status report advising the District Court that they would conduct an environmental assessment to remedy the National Environmental Policy Act defect found by the Tenth Circuit, and that the draft environmental assessment would be completed and ready for public review and comment on or before June 30, 2018. On April 19, 2018 the court orally denied plaintiffs’ request for remedy briefing without prejudice. Plaintiffs may renew their request if BLM does not submit a draft environmental assessment by the end of July 2018. The Company’s operations will continue in the normal course during this period since the decision has no impact on mining at this time. The Company currently believes that its operations are unlikely to be materially impacted by this case, but the timing and magnitude of any impact on the Company’s future operations is not certain. Wilpinjong Extension Project (WEP). Wollar Progress Association has applied to the Land & Environment Court for a judicial review of the New South Wales Planning Assessment Commission’s decision to approve the WEP. The matter was heard by the court in early February 2018. However, a decision has not yet been ordered. In the interim, the Company’s Wilpinjong Mine continues to mine in accordance with its approvals. Central Arizona Water Conservation District (CAWCD). On May 1, 2018, the Company, along with the Hopi Tribe and the United Mine Workers of America, filed a lawsuit against the CAWCD. CAWCD operates, on behalf of the Bureau of Reclamation, the Central Arizona Project (CAP), an aqueduct system that brings water from the Colorado River to three counties in Arizona. CAWCD historically obtained most of CAP’s power requirements from the Navajo Generating Station (NGS), which is served by a single Peabody mine. NGS is owned by several private companies and one governmental entity. The non-governmental owners of NGS issued a statement that they do not currently intend to be the operators of the plant beyond December 2019. A number of potential investors have expressed interest in pursuing an ownership position in NGS. Recently, CAWCD made the decision to obtain CAP’s power requirements from sources other than NGS for 2020 and thereafter. The lawsuit seeks a determination that federal law requires CAWCD to obtain CAP’s power requirements from NGS. Other At times the Company becomes a party to other disputes, including those related to contract miner performance, claims, lawsuits, arbitration proceedings, regulatory investigations and administrative procedures in the ordinary course of business in the U.S., Australia and other countries where the Company does business. Based on current information, the Company believes that such other pending or threatened proceedings are likely to be resolved without a material adverse effect on its financial condition, results of operations or cash flows.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information The Company reports its results of operations through the following reportable segments: Powder River Basin Mining, Midwestern U.S. Mining, Western U.S. Mining, Australian Metallurgical Mining, Australian Thermal Mining, Trading and Brokerage and Corporate and Other. The Company’s chief operating decision maker uses Adjusted EBITDA as the primary metric to measure the segments’ operating performance. Adjusted EBITDA is a non-GAAP measure defined as income (loss) from continuing operations before deducting net interest expense, income taxes, asset retirement obligation expenses, depreciation, depletion and amortization and reorganization items, net. Adjusted EBITDA is also adjusted for the discrete items that management excluded in analyzing the segments’ operating performance, as displayed in the reconciliation below. Management believes non-GAAP performance measures are used by investors to measure the Company’s operating performance and lenders to measure the Company’s ability to incur and service debt. Adjusted EBITDA is not intended to serve as an alternative to U.S. GAAP measures of performance and may not be comparable to similarly-titled measures presented by other companies. Reportable segment results were as follows: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Revenues: Powder River Basin Mining $ 389.3 $ 394.3 Midwestern U.S. Mining 201.7 193.2 Western U.S. Mining 143.7 149.7 Australian Metallurgical Mining 466.2 328.9 Australian Thermal Mining 201.4 224.8 Trading and Brokerage 20.1 15.0 Corporate and Other 40.3 20.3 Total $ 1,462.7 $ 1,326.2 Adjusted EBITDA: Powder River Basin Mining $ 74.5 $ 91.7 Midwestern U.S. Mining 31.2 50.0 Western U.S. Mining 32.0 50.0 Australian Metallurgical Mining 166.4 109.6 Australian Thermal Mining 61.6 75.6 Trading and Brokerage 1.2 8.8 Corporate and Other (1) (3.0 ) (44.4 ) Total $ 363.9 $ 341.3 (1) Includes the gain of $20.6 million on the sale of certain surplus land assets in Queensland and the gain of $7.1 million recognized on the sale of the Company’s interest in the RMJV during the three months ended March 31, 2018 and the gain of $19.7 million recognized on the sale of Dominion Terminal Associates during the three months ended March 31, 2017, as described in Note 15. “Other Events”. A reconciliation of consolidated income from continuing operations, net of income taxes to Adjusted EBITDA follows: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Income from continuing operations, net of income taxes $ 208.3 $ 124.3 Depreciation, depletion and amortization 169.6 119.9 Asset retirement obligation expenses 12.3 14.6 Asset impairment — 30.5 Changes in deferred tax asset valuation allowance and amortization of basis difference related to equity affiliates (7.6 ) (5.2 ) Interest expense 36.3 32.9 Interest income (7.2 ) (2.7 ) Reorganization items, net (12.8 ) 41.4 Unrealized gains on economic hedges (38.6 ) (16.6 ) Unrealized losses on non-coal trading derivative contracts 1.8 — Take-or-pay contract-based intangible recognition (8.3 ) — Income tax provisi on 10.1 2.2 Total Adjusted EBITDA $ 363.9 $ 341.3

Basis of Presentation Basis of

Basis of Presentation Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Basis of Presentation [Abstract]
Plan of Reorganization and Emergence from Chapter 11 Cases [Policy Text Block]	Plan of Reorganization and Emergence from Chapter 11 Cases On April 13, 2016, PEC and a majority of its wholly owned domestic subsidiaries, as well as one international subsidiary in Gibraltar (collectively with PEC, the Debtors), filed voluntary petitions (the Bankruptcy Petitions) under Chapter 11 of Title 11 of the U.S. Code (the Bankruptcy Code) in the United States Bankruptcy Court for the Eastern District of Missouri (the Bankruptcy Court). The Debtors’ Chapter 11 cases (the Chapter 11 Cases) were jointly administered under the caption In re Peabody Energy Corporation, et al. , Case No. 16-42529. For periods subsequent to filing the Bankruptcy Petitions, the Company applied the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 852, “Reorganizations”, in preparing its consolidated financial statements. ASC 852 requires that financial statements distinguish transactions and events that are directly associated with the reorganization from the ongoing operations of the business. Accordingly, certain revenues, expenses, realized gains and losses and provisions for losses that were realized or incurred in the bankruptcy proceedings were recorded in “Reorganization items, net” in the unaudited condensed consolidated statements of operations. “Reorganization items, net” for the three months ended March 31, 2018 consisted of settlement gains of $12.8 million related to certain unsecured claims. For the three months ended March 31, 2017, “Reorganization items, net” consisted of professional fees of $42.5 million , accounts payable settlement gains of $0.7 million and interest income of $0.4 million . Professional fees are only those that were directly related to the reorganization including, but not limited to, fees associated with advisors to the Debtors, the unsecured creditors' committee and certain other secured and unsecured creditors. During the three months ended March 31, 2017 , $31.4 million of cash payments were made for "Reorganization items, net". On March 17, 2017, the Bankruptcy Court entered an order, Docket No. 2763 (the Confirmation Order), confirming the Debtors’ Second Amended Joint Plan of Reorganization of Debtors and Debtors in Possession (as further modified, the Plan). On April 3, 2017 (the Effective Date), the Debtors satisfied the conditions to effectiveness set forth in the Plan, the Plan became effective in accordance with its terms and the Debtors emerged from the Chapter 11 Cases. On the Effective Date, in accordance with ASC 852, the Company applied fresh start reporting which requires the Company to allocate its reorganization value to the fair value of assets and liabilities in conformity with the guidance for the acquisition method of accounting for business combinations. The Company was permitted to use fresh start reporting because (i) the holders of existing voting shares of the Predecessor (as defined below) company received less than 50% of the voting shares of the emerging entity upon reorganization and (ii) the reorganization value of the Company’s assets immediately prior to Plan confirmation was less than the total of all postpetition liabilities and allowed claims. Upon adoption of fresh start reporting, the Company became a new entity for financial reporting purposes, reflecting the Successor (as defined below) capital structure. As a result, a new accounting basis in the identifiable assets and liabilities assumed was established with no retained earnings or accumulated other comprehensive income (loss) for financial reporting purposes. The Company selected an accounting convenience date of April 1, 2017 for purposes of applying fresh start reporting as the activity between the convenience date and the Effective Date does not result in a material difference in the results. References to “Successor” in the financial statements and accompanying footnotes are in reference to reporting dates on or after April 2, 2017; references to “Predecessor” in the financial statements and accompanying footnotes are in reference to reporting dates through April 1, 2017 which includes the impact of the Plan provisions and the application of fresh start reporting. As such, the Company’s financial statements for the Successor will not be comparable in many respects to its financial statements for periods prior to the adoption of fresh start reporting and prior to the accounting for the effects of the Plan. For further information on the Plan and fresh start reporting, see Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 . In connection with fresh start reporting, the Company made certain prospective accounting policy elections that impact the Successor periods presented herein. The Company now classifies the amortization associated with its asset retirement obligation assets within “Depreciation, depletion and amortization” in its consolidated statements of operations, rather than within “Asset retirement obligation expenses”, as in Predecessor periods. With respect to its accrued postretirement benefit and pension obligations, the Company now records amounts attributable to prior service cost and actuarial valuation changes, as applicable, currently in earnings rather than recording such amounts within accumulated other comprehensive income and amortizing to expense over applicable time periods.

Revenues (Policies)

Revenues (Policies)	3 Months Ended
	Mar. 31, 2018
Revenue Recognition [Abstract]
Revenue Recognition, Policy [Policy Text Block]	The Company’s revenue from coal sales is realized and earned when risk of loss passes to the customer. Under the typical terms of the Company’s coal supply agreements, title and risk of loss transfer to the customer at the mine or port, where coal is loaded to the transportation source(s) that serves each of the Company’s mines. The Company incurs certain “add-on” taxes and fees on coal sales. Reported coal sales include taxes and fees charged by various federal and state governmental bodies and the freight charged on destination customer contracts.
Sales Revenues [Policy Text Block]	Sales The majority of the Company’s revenue is derived from the sale of coal under a variety of long-term (those with initial terms of one year or longer and which often include price reopener and/or extension provisions), short-term (those with terms of less than one year) and spot agreements. The Company’s revenue from coal sales is realized and earned when risk of loss passes to the customer. Under the typical terms of the Company’s coal supply agreements, title and risk of loss transfer to the customer at the mine or port, where coal is loaded to the transportation source(s) that serves each of the Company’s mines. The Company incurs certain “add-on” taxes and fees on coal sales. Reported coal sales include taxes and fees charged by various federal and state governmental bodies and the freight charged on destination customer contracts. The Company’s U.S. operating platform primarily sells thermal coal to electric utilities in the U.S. under long-term contracts, with a portion sold into the seaborne markets as conditions warrant. A significant portion of the coal production from the U.S. mining segments is sold under long-term supply agreements, and customers of those segments continue to pursue long-term sales agreements in recognition of the importance of reliability, service and predictable coal prices to their operations. The terms of coal supply agreements result from competitive bidding and extensive negotiations with customers. Consequently, the terms of those agreements may vary in many respects, including price adjustment features, price reopener terms, coal quality requirements, quantity parameters, permitted sources of supply, treatment of environmental constraints, extension options, force majeure and termination and assignment provisions. The Company's Australian operating platform is primarily export focused with customers spread across several countries, while a portion of the metallurgical and thermal coal is sold within Australia. Generally, revenues from individual countries vary year by year based on electricity and steel demand, the strength of the global economy, governmental policies and several other factors, including those specific to each country. A majority of these sales are executed through annual and multi-year international coal supply agreements that contain provisions requiring both parties to renegotiate pricing periodically. Industry commercial practice, and the Company’s typical practice, is to negotiate pricing for seaborne metallurgical coal contracts on a quarterly, spot or index basis and seaborne thermal coal contracts on an annual, spot or index basis. The portion of volume priced on a shorter-term basis and index linked basis has increased in recent years. In the case of periodically negotiated pricing, the Company may deliver coal under provisional pricing until a final agreed-upon price is determined. The resulting make-whole settlements are recognized when reasonably estimable. Contract pricing is set forth on a per ton basis and revenue is generally recorded as the product of price and volume delivered. Many of the Company’s coal supply agreements contain provisions that permit the parties to adjust the contract price upward or downward at specified times. These contract prices may be adjusted based on inflation or deflation and/or changes in the factors affecting the cost of producing coal, such as taxes, fees, royalties and changes in the laws regulating the mining, production, sale or use of coal. In a limited number of contracts, failure of the parties to agree on a price under those provisions may allow either party to terminate the contract. The Company sometimes experiences a reduction in coal prices in new long-term coal supply agreements replacing some of its expiring contracts. Coal supply agreements also typically contain force majeure provisions allowing temporary suspension of performance by the Company or the customer during the duration of specified events beyond the control of the affected party. Most of the coal supply agreements contain provisions requiring the Company to deliver coal meeting quality thresholds for certain characteristics such as Btu, sulfur content, ash content, grindability and ash fusion temperature. Failure to meet these specifications could result in economic penalties, including price adjustments, the rejection of deliveries or termination of the contracts. Moreover, some of these agreements allow the Company’s customers to terminate their contracts in the event of changes in regulations affecting the industry that restrict the use or type of coal permissible at the customer’s plant or increase the price of coal beyond specified limits.
Other Revenues [Policy Text Block]	Other Revenues "Other revenues" may include net revenues from coal trading activities as discussed in Note 7. “Coal Trading,” as well as coal sales revenues that were derived from the Company’s mining operations and sold through the Company’s coal trading business. Also included are revenues from customer contract-related payments, royalties related to coal lease agreements, sales agency commissions, farm income, and property and facility rentals. Royalty income generally results from the lease or sublease of mineral rights to third parties, with payments based upon a percentage of the selling price or an amount per ton of coal produced.

Derivatives and Fair Value Me31

Derivatives and Fair Value Measurements (Policies)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Corporate Hedging [Policy Text Block]	The Company is exposed to several risks in the normal course of business, including (1) foreign currency exchange rate risk for non-U.S. dollar expenditures and balances, (2) price risk on coal produced by and diesel fuel utilized in the Company’s mining operations and (3) interest rate risk that has been partially mitigated by fixed rates on long-term debt. The Company manages a portion of its price risk related to the sale of coal (excluding coal trading activities) using long-term coal supply agreements, rather than using derivative instruments. Derivative financial instruments have historically been used to manage the Company’s risk exposure to foreign currency exchange rate risk, primarily on Australian dollar expenditures made in its Australian mining platform. This risk was historically managed using forward contracts and options designated as cash flow hedges, with the objective of reducing the variability of cash flows associated with forecasted foreign currency expenditures. The Company has also used derivative instruments to manage its exposure to the variability of diesel fuel prices used in production in the U.S. and Australia with swaps or options, which it has also designated as cash flow hedges, with the objective of reducing the variability of cash flows associated with forecasted diesel fuel purchases. These risk management activities are collectively referred to as “Corporate Hedging” and are actively monitored for compliance with the Company’s risk management policies.
Fair Value Transfer, Policy [Policy Text Block]	The Company’s policy is to value all transfers between levels using the beginning of period valuation.

Coal Trading (Policies)

Coal Trading (Policies)	3 Months Ended
	Mar. 31, 2018
Coal Trading [Abstract]
Offsetting and Balance Sheet Presentation of Coal Trading Assets and Liabilities [Policy Text Block]	The Company offsets its coal trading asset and liability derivative positions, and variation margin related to those positions, on a counterparty-by-counterparty basis in the condensed consolidated balance sheets, with the fair values of those respective derivatives reflected in “Assets from coal trading activities, net” and “Liabilities from coal trading activities, net.”
Fair Value Valuation Techniques for Level 1 and 2 Financial Assets and Liabilities [Policy Text Block]	For Level 1 and 2 financial assets and liabilities, the Company utilizes both direct and indirect observable price quotes, including U.S. interest rate curves; LIBOR yield curves; Chicago Mercantile Exchange Group, Intercontinental Exchange, Baltic Exchange and Singapore Exchange contract prices; broker quotes; published indices; and other market quotes. Below is a summary of the Company’s valuation techniques for Level 1 and 2 financial assets and liabilities: • Futures, swaps and options: generally valued based on unadjusted quoted prices in active markets (Level 1) or a valuation that is corroborated by the use of market-based pricing (Level 2) except when credit and non-performance risk is considered to be a significant input (greater than 10% of fair value), then the Company classifies as Level 3. • Physical purchase/sale contracts: purchases and sales at locations with significant market activity corroborated by market-based information (Level 2) except when credit and non-performance risk is considered to be a significant input (greater than 10% of fair value), then the Company classifies as Level 3.
Concentration Risk, Credit Risk, Policy	Credit and Non-performance Risk. The fair value of the Company’s coal derivative assets and liabilities reflects adjustments for credit risk. The Company’s exposure is substantially with electric utilities, energy marketers, steel producers and nonfinancial trading houses. The Company’s policy is to independently evaluate each customer’s creditworthiness prior to entering into transactions and to regularly monitor the credit extended. If the Company engages in a transaction with a counterparty that does not meet its credit standards, the Company seeks to protect its position by requiring the counterparty to provide an appropriate credit enhancement. Also, when appropriate (as determined by its credit management function), the Company has taken steps to reduce its exposure to customers or counterparties whose credit has deteriorated and who may pose a higher risk of failure to perform under their contractual obligations. These steps include obtaining letters of credit or cash collateral (margin), requiring prepayments for shipments or the creation of customer trust accounts held for the Company’s benefit to serve as collateral in the event of a failure to pay or perform. To reduce its credit exposure related to trading and brokerage activities, the Company seeks to enter into netting agreements with counterparties that permit the Company to offset asset and liability positions with such counterparties and, to the extent required, the Company will post or receive margin amounts associated with exchange-cleared and certain OTC positions. The Company also continually monitors counterparty and contract non-performance risk, if present, on a case-by-case basis.

Newly Adopted Accounting Stan33

Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented (Tables)	3 Months Ended
	Mar. 31, 2018
Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	Newly Adopted Accounting Standards Revenue Recognition. In May 2014, the FASB issued Accounting Standards Update (ASU) 2014-09, “Revenue from Contracts with Customers (Topic 606)”, that requires recognition of revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which a company expects to be entitled in exchange for those goods or services. The FASB has also issued several updates to ASU 2014-09. On January 1, 2018, the Company adopted ASU 2014-09 using the modified retrospective method. The new standard provides a single principles-based, five-step model to be applied to all contracts with customers, which steps are to (1) identify the contract(s) with the customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract and (5) recognize revenue when each performance obligation is satisfied. The Company recognized the cumulative effect of initially applying ASU 2014-09 as an adjustment to the opening balance of retained earnings. Revenue previously recognized under contracts completed prior to January 1, 2018 was not impacted by adoption and comparative information has not been restated. The impact of the adoption of ASU 2014-09 is expected to be immaterial to the Company’s results of operations, financial condition, and cash flows on an ongoing basis. The majority of the Company’s coal sales revenue will continue to be recognized as title and risk of loss transfer to the customer at mines and ports when coal is loaded to the transportation source, as further described in Note 3. “Revenue Recognition.” The impact of the adoption of ASU 2014-09 was limited to a long-term contract in which consideration related to the reimbursement of certain post-mining costs was recognized as costs were incurred, which differs in timing compared to the five-step model described above. The cumulative effects to the Company’s consolidated January 1, 2018 balance sheet were to reduce retained earnings for the amount of revenue that would have been deferred and to reduce long-term customer receivables, as noted in the table below: Balance at December 31, 2017 Adjustments due to ASU 2014-09 Balance at January 1, 2018 (Dollars in millions) ASSETS Investments and other assets $ 470.6 $ (22.5 ) $ 448.1 STOCKHOLDERS’ EQUITY Retained earnings 613.6 (22.5 ) 591.1 ASU 2014-09 also requires entities to disclose sufficient qualitative and quantitative information to enable financial statement users to understand the nature, amount, timing and uncertainty of revenues and cash flows arising from contracts with customers. Such disclosures are included in Note 3. “Revenue Recognition.” Classification of Certain Cash Receipts and Cash Payments . In August 2016, the FASB issued ASU 2016-15 to amend the classification of certain cash receipts and cash payments in the statement of cash flows to reduce diversity in practice. The Company retrospectively adopted all the provisions of this new standard in the first quarter of 2018. The classification requirements under the new guidance are either consistent with the Company’s current practices or are not applicable to its activities, and as such, did not have a material impact on classification of cash receipts and cash payments in the Company’s unaudited condensed consolidated statements of cash flows. Restricted Cash . In November 2016, the FASB issued ASU 2016-18, which reduces diversity in the presentation of restricted cash and restricted cash equivalents in the statement of cash flows. The Company retrospectively adopted all the provisions of this new accounting standard in the first quarter of 2018 and as a result of the new guidance, the Company will combine restricted cash with unrestricted cash and cash equivalents when reconciling the beginning and end of period balances on its statements of cash flows. The amendments also require a company to disclose information about the nature of the restrictions and amounts described as restricted cash and restricted cash equivalents. Such disclosures are included in Note 17. “Financial Instruments and Other Guarantees.” Further, as cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet, the Company reconciled these amounts to the total shown in the statement of cash flows in a tabular format within the Company’s unaudited condensed consolidated statements of cash flows. Compensation - Retirement Benefits . In March 2017, the FASB issued ASU 2017-07, which requires employers that sponsor defined benefit pension and other postretirement plans to report the service cost component in the same line item as other compensation costs and to report the other components of net periodic benefit costs (which include interest costs, expected return on plan assets, amortization of prior service cost or credits and actuarial gains and losses) separately and outside a subtotal of operating income on a retrospective basis. The guidance limiting the capitalization of net periodic benefit cost in assets to the service cost component will be applied prospectively. The Company adopted all the provisions of this new accounting standard in the first quarter of 2018. While adoption of this guidance did impact financial statement presentation, it did not materially impact the Company’s results of operations, financial condition, or cash flows. The retrospective impact to the unaudited condensed consolidated statement of operations was as follows: Predecessor Three Months Ended March 31, 2017 Before Application of Accounting Guidance Adjustment After Application of Accounting Guidance (Dollars in millions) Results of Operations Amounts Operating costs and expenses $ 963.7 $ (13.5 ) $ 950.2 Selling and administrative expenses 37.2 (0.9 ) 36.3 Operating profit 198.1 14.4 212.5 Net periodic benefit costs, excluding service cost — 14.4 14.4 Income from continuing operations before income taxes 126.5 — 126.5 Compensation - Stock Compensation. In May 2017, the FASB issued ASU 2017-09 to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The Company prospectively applied all the provisions of this new accounting standard on January 1, 2018 and there was no material impact to the Company’s financial statements. Accounting Standards Not Yet Implemented Leases. In February 2016, the FASB issued ASU 2016-02, which will require a lessee to recognize on its balance sheet a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term for leases with lease terms of more than 12 months. Consistent with current U.S. GAAP, the recognition, measurement and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance or operating lease. Additional qualitative disclosures along with specific quantitative disclosures will also be required. The new guidance will take effect for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018 (January 1, 2019 for the Company). In November 2017, the FASB voted to propose amendments to the new leases guidance to add two practical expedients. The proposed changes would allow entities to elect a simplified transition approach, and provide lessors with an option related to how lease and other related revenues are presented and disclosed. The Company is in the process of evaluating the impact of ASU 2016-02 and expects, through the addition of significant lease assets and lease liabilities to the consolidated balance sheet, ASU 2016-02 will have a material impact on the consolidated balance sheets (amount will be dependent on leases outstanding at adoption date), but is not expected to have a material impact on the consolidated statements of operations and comprehensive income (loss) of the Company. Financial Instruments - Credit Losses. In June 2016, the FASB issued ASU 2016-13 related to the measurement of credit losses on financial instruments. The pronouncement replaces the incurred loss methodology to record credit losses with a methodology that reflects the expected credit losses for financial assets not accounted for at fair value with gains and losses recognized through net income. This standard is effective for fiscal years beginning after December 15, 2019 (January 1, 2020 for the Company) and interim periods therein, with early adoption permitted for fiscal years, and interim periods therein, beginning after December 15, 2018. The Company is in the process of evaluating the impact that the adoption of this guidance will have on its results of operations, financial condition, cash flows and financial statement presentation. Derivatives and Hedging. In August 2017, the FASB issued ASU 2017-12 to amend the hedge accounting rules to simplify the application of hedge accounting guidance and better align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The guidance expands the ability to hedge nonfinancial and financial risk components, reduces complexity in fair value hedges of interest rate risk, eliminates the requirement to separately measure and report hedge ineffectiveness, as well as eases certain hedge effectiveness assessment requirements. The new guidance will be effective for fiscal years beginning after December 15, 2018 (January 1, 2019 for the Company) and interim periods therein, with early adoption permitted. The amendments to cash flow and net investment hedge relationships that exist on the date of adoption will be applied using a modified retrospective approach. The presentation and disclosure requirements will be applied prospectively. The Company is currently evaluating the impact that the adoption of this guidance will have on its results of operations, financial condition, cash flows and financial statement presentation. Leases - Land Easements. In January 2018, the FASB issued ASU 2018-01 to provide an optional transition practical expedient to not evaluate under Topic 842 existing or expired land easements that were not previously accounted for as leases under the current guidance in Topic 840. An entity that elects this practical expedient should evaluate new or modified land easements under Topic 842 beginning at the date that the entity adopts Topic 842. An entity that does not elect this practical expedient should evaluate all existing or expired land easements in connection with the adoption of the new leases requirements in Topic 842 to assess whether they meet the definition of a lease. The amendments in this update affect the amendments in ASU 2016-02. The effective date and transition requirements for the amendments are the same as the effective date and transition requirements in ASU 2016-02. The Company is in the process of evaluating the impact that the adoption of this guidance will have on its results of operations, financial condition, cash flows and financial statement presentation.

Revenues (Tables)

Revenues (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue Recognition [Abstract]
Schedule of Accounts Receivable [Table Text Block]	Accounts receivable, net at March 31, 2018 and December 31, 2017 consisted of the following: March 31, 2018 December 31, 2017 (Dollars in millions) Trade receivables, net $ 388.0 $ 504.2 Miscellaneous receivables, net 136.0 47.9 Accounts receivable, net $ 524.0 $ 552.1
Disaggregation of Revenue by Product Type and Market [Table Text Block]	With respect to its Australian Mining segments, the Company classifies as “Export” certain revenue from domestically-delivered coal under contracts in which the price is derived on a basis similar to export contracts. Successor Three Months Ended March 31, 2018 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Thermal coal Domestic $ 389.2 $ 200.9 $ 130.3 $ — $ 36.1 $ — $ — $ 756.5 Export — 0.7 8.0 — 164.9 — — 173.6 Total thermal 389.2 201.6 138.3 — 201.0 — — 930.1 Metallurgical coal Export — — — 465.3 — — — 465.3 Total metallurgical — — — 465.3 — — — 465.3 Other 0.1 0.1 5.4 0.9 0.4 20.1 40.3 67.3 Total revenues $ 389.3 $ 201.7 $ 143.7 $ 466.2 $ 201.4 $ 20.1 $ 40.3 $ 1,462.7 Predecessor Three Months Ended March 31, 2017 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Thermal coal Domestic $ 394.3 $ 193.2 $ 133.5 $ — $ 27.3 $ — $ — $ 748.3 Export — — — — 197.2 — — 197.2 Total thermal 394.3 193.2 133.5 — 224.5 — — 945.5 Metallurgical coal Export — — — 324.6 — — — 324.6 Total metallurgical — — — 324.6 — — — 324.6 Other — — 16.2 4.3 0.3 15.0 20.3 56.1 Total revenues $ 394.3 $ 193.2 $ 149.7 $ 328.9 $ 224.8 $ 15.0 $ 20.3 $ 1,326.2
Disaggregation of Revenue by Contract Duration [Table Text Block]	Revenue by contract duration was as follows: Successor Three Months Ended March 31, 2018 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Long-term contracts $ 211.8 $ 106.4 $ 117.7 $ 7.6 $ 44.6 $ — $ — $ 488.1 Short-term contracts 131.6 81.2 9.6 389.9 132.7 — — 745.0 Spot 45.8 14.0 11.0 67.8 23.7 — — 162.3 Other 0.1 0.1 5.4 0.9 0.4 20.1 40.3 67.3 Total revenues $ 389.3 $ 201.7 $ 143.7 $ 466.2 $ 201.4 $ 20.1 $ 40.3 $ 1,462.7 Predecessor Three Months Ended March 31, 2017 Powder River Basin Mining Midwestern U.S. Mining Western U.S. Mining Australian Metallurgical Mining Australian Thermal Mining Trading and Brokerage Corporate and Other Consolidated (Dollars in millions) Long-term contracts $ 238.5 $ 130.0 $ 119.4 $ 4.9 $ 33.4 $ — $ — $ 526.2 Short-term contracts 119.2 63.2 9.9 235.7 100.7 — — 528.7 Spot 36.6 — 4.2 84.0 90.4 — — 215.2 Other — — 16.2 4.3 0.3 15.0 20.3 56.1 Total revenues $ 394.3 $ 193.2 $ 149.7 $ 328.9 $ 224.8 $ 15.0 $ 20.3 $ 1,326.2

Discontinued Operations (Tables

Discontinued Operations (Tables)	3 Months Ended
	Mar. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Summarized results of discontinued operations	Results from discontinued operations were as follows during the periods presented below: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Loss from discontinued operations, net of income taxes $ (1.3 ) $ (4.1 ) Assets and Liabilities of Discontinued Operations Assets and liabilities classified as discontinued operations included in the Company’s condensed consolidated balance sheets were as follows: March 31, 2018 December 31, 2017 (Dollars in millions) Assets: Other current assets $ 0.6 $ 0.3 Total assets classified as discontinued operations $ 0.6 $ 0.3 Liabilities: Accounts payable and accrued expenses $ 70.7 $ 70.6 Other noncurrent liabilities 170.6 170.0 Total liabilities classified as discontinued operations $ 241.3 $ 240.6

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories as of March 31, 2018 and December 31, 2017 consisted of the following: March 31, 2018 December 31, 2017 (Dollars in millions) Materials and supplies $ 103.1 $ 101.5 Raw coal 56.6 78.1 Saleable coal 105.8 111.7 Total $ 265.5 $ 291.3

Derivatives and Fair Value Me37

Derivatives and Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Classification and amounts of pre-tax gains and losses related to the Company's non coal-trading hedges	The tables below show the classification and amounts of pre-tax gains and losses related to the Company’s Corporate Hedging derivatives: Successor Three Months Ended March 31, 2018 Financial Instrument Income Statement Classification of Losses Total loss recognized in income Loss realized in income on derivatives Unrealized loss recognized in income on non-designated derivatives (Dollars in millions) Foreign currency option contracts Operating costs and expenses $ (4.2 ) $ (2.4 ) $ (1.8 ) Total $ (4.2 ) $ (2.4 ) $ (1.8 ) Predecessor Three Months Ended March 31, 2017 Financial Instrument Income Statement Classification of Losses Total loss recognized in income Loss reclassified from other comprehensive loss into income (Dollars in millions) Commodity swap contracts Operating costs and expenses $ (11.0 ) $ (11.0 ) Foreign currency forward contracts Operating costs and expenses (16.6 ) (16.6 ) Total $ (27.6 ) $ (27.6 )
Fair Value, Assets Measured on Recurring Basis [Table Text Block]	The following tables set forth the hierarchy of the Company’s net financial asset positions for which fair value is measured on a recurring basis: March 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Foreign currency contracts $ — $ 2.3 $ — $ 2.3 Total net financial assets $ — $ 2.3 $ — $ 2.3 December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in millions) Foreign currency contracts $ — $ 4.2 $ — $ 4.2 Total net financial assets $ — $ 4.2 $ — $ 4.2
Carrying amounts and estimated fair values of the Company's debt	The carrying amounts and estimated fair values of the Company’s current and long-term debt as of March 31, 2018 and December 31, 2017 are summarized as follows: March 31, 2018 December 31, 2017 Carrying Estimated Carrying Estimated (Dollars in millions) Current and Long-term debt $ 1,455.2 $ 1,535.6 $ 1,460.8 $ 1,547.4

Coal Trading (Tables)

Coal Trading (Tables)	3 Months Ended
	Mar. 31, 2018
Coal Trading [Abstract]
Trading revenues by type of instrument	Trading revenues (losses) recognized during the periods presented below were as follows: Successor Predecessor Trading Revenues by Type of Instrument Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Futures, swaps and options $ (16.9 ) $ (10.2 ) Physical purchase/sale contracts 37.0 25.2 Total trading revenues $ 20.1 $ 15.0
Fair value of assets and liabilities from coal trading activities and related balance sheet offsetting disclosures	The fair value of assets and liabilities from coal trading activities presented on a gross and net basis as of March 31, 2018 and December 31, 2017 is set forth below: Affected Line Item in the Condensed Consolidated Balance Sheets Gross Amounts of Recognized Assets (Liabilities) Gross Amounts Offset in the Condensed Consolidated Balance Sheets Variation Margin Posted (1) Net Amounts of Assets (Liabilities) Presented in the Condensed Consolidated Balance Sheets (Dollars in millions) Fair Value as of March 31, 2018 Assets from coal trading activities, net $ 53.6 $ (42.4 ) $ — $ 11.2 Liabilities from coal trading activities, net (57.9 ) 42.4 6.7 (8.8 ) Total, net $ (4.3 ) $ — $ 6.7 $ 2.4 Fair Value as of December 31, 2017 Assets from coal trading activities, net $ 77.1 $ (74.5 ) $ — $ 2.6 Liabilities from coal trading activities, net (122.0 ) 74.5 35.8 (11.7 ) Total, net $ (44.9 ) $ — $ 35.8 $ (9.1 ) (1) None of the net variation margin posted at March 31, 2018 and December 31, 2017 related to cash flow hedges.
Fair value coal trading net assets (liabilities) measured on recurring basis	The following tables set forth the hierarchy of the Company’s net financial asset (liability) coal trading positions for which fair value is measured on a recurring basis as of March 31, 2018 and December 31, 2017 : March 31, 2018 Level 1 Level 2 Level 3 Total (Dollars in millions) Futures, swaps and options $ 0.2 $ — $ — $ 0.2 Physical purchase/sale contracts — 2.2 — 2.2 Total net financial assets $ 0.2 $ 2.2 $ — $ 2.4 December 31, 2017 Level 1 Level 2 Level 3 Total (Dollars in millions) Futures, swaps and options $ (3.0 ) $ (4.2 ) $ — $ (7.2 ) Physical purchase/sale contracts — (1.9 ) — (1.9 ) Total net financial liabilities $ (3.0 ) $ (6.1 ) $ — $ (9.1 )
Schedule Of Future Realization Of Trading Portfolio	As of March 31, 2018 , the timing of the estimated future realization of the value of the Company’s trading portfolio was as follows: Percentage of Year of Expiration Portfolio Total 2018 83 % 2019 25 % 2020 (8 )% 100 %

Intangible Contract Assets an39

Intangible Contract Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue Recognition [Abstract]
Schedule Of Intangible Assets And Liabilities	The balances and respective balance sheet classifications of such assets and liabilities at March 31, 2018 and December 31, 2017 , net of accumulated amortization, are set forth in the following tables: March 31, 2018 (Dollars in millions) Assets Liabilities Net Total Coal supply agreements $ 143.8 $ (38.6 ) $ 105.2 Take-or-pay contracts — (81.1 ) (81.1 ) Total $ 143.8 $ (119.7 ) $ 24.1 Balance sheet classification: Investments and other assets $ 143.8 $ — $ 143.8 Accounts payable and accrued expenses — (25.1 ) (25.1 ) Other noncurrent liabilities — (94.6 ) (94.6 ) Total $ 143.8 $ (119.7 ) $ 24.1 December 31, 2017 (Dollars in millions) Assets Liabilities Net Total Coal supply agreements $ 177.2 $ (42.7 ) $ 134.5 Take-or-pay contracts — (90.7 ) (90.7 ) Total $ 177.2 $ (133.4 ) $ 43.8 Balance sheet classification: Investments and other assets $ 177.2 $ — $ 177.2 Accounts payable and accrued expenses — (27.6 ) (27.6 ) Other noncurrent liabilities — (105.8 ) (105.8 ) Total $ 177.2 $ (133.4 ) $ 43.8

Property, Plant, Equipment an40

Property, Plant, Equipment and Mine Development (Tables)	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	The composition of property, plant, equipment and mine development, net, as of March 31, 2018 and December 31, 2017 is set forth in the table below. Refer to Note 2. “Emergence from the Chapter 11 Cases and Fresh Start Reporting” in the Company's Annual Report on Form 10-K for the year ended December 31, 2017 for details regarding the impact of fresh start reporting on property, plant, equipment and mine development. March 31, 2018 December 31, 2017 (Dollars in millions) Land and coal interests $ 3,891.7 $ 3,890.5 Buildings and improvements 452.3 470.6 Machinery and equipment 1,195.1 1,149.3 Less: Accumulated depreciation, depletion and amortization (531.1 ) (398.5 ) Property, plant, equipment and mine development, net $ 5,008.0 $ 5,111.9

Long-term Debt (Tables)

Long-term Debt (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	In accordance with the Plan, the Company was recapitalized with new debt and equity instruments, including the 6.000% Senior Secured Notes due March 2022, the 6.375% Senior Secured Notes due March 2025, and the Senior Secured Term Loan due 2025 in the table below. The Company’s total indebtedness as of March 31, 2018 and December 31, 2017 consisted of the following: March 31, 2018 December 31, 2017 (Dollars in millions) 6.000% Senior Secured Notes due March 2022 $ 500.0 $ 500.0 6.375% Senior Secured Notes due March 2025 500.0 500.0 Senior Secured Term Loan due 2025 444.3 444.2 Capital lease and other obligations 67.8 76.0 Less: Debt issuance costs (56.9 ) (59.4 ) 1,455.2 1,460.8 Less: Current portion of long-term debt 87.1 42.1 Long-term debt $ 1,368.1 $ 1,418.7

Pension and Postretirement Be42

Pension and Postretirement Benefit Costs (Tables)	3 Months Ended
	Mar. 31, 2018
Defined benefit pension plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Net Benefit Costs	Net periodic pension (benefit) cost included the following components: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Service cost for benefits earned $ 0.6 $ 0.6 Interest cost on projected benefit obligation 7.8 9.7 Expected return on plan assets (10.7 ) (11.0 ) Amortization of prior service cost and net actuarial loss — 6.4 Net periodic pension (benefit) cost $ (2.3 ) $ 5.7
Postretirement benefit plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Net Benefit Costs	Net periodic postretirement benefit cost included the following components: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Service cost for benefits earned $ 2.0 $ 2.3 Interest cost on accumulated postretirement benefit obligation 7.1 8.4 Amortization of prior service cost and net actuarial loss — 3.2 Net periodic postretirement benefit cost $ 9.1 $ 13.9

Accumulated Other Comprehensi43

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
After-tax components of comprehensive income (loss)	The following table sets forth the after-tax components of accumulated other comprehensive income and changes thereto recorded during the three months ended March 31, 2018 : Foreign Currency Translation Adjustment Total Accumulated Other Comprehensive Income (Dollars in millions) December 31, 2017 $ 1.4 $ 1.4 Current period change (0.8 ) (0.8 ) March 31, 2018 $ 0.6 $ 0.6
Reclassification out of accumulated other comprehensive income (loss)	The following table provides additional information regarding items reclassified out of “Accumulated other comprehensive income (loss)” into earnings during the period presented below: Amount reclassified from accumulated other comprehensive income (loss) (1) Predecessor Details about accumulated other comprehensive income (loss) components Three Months Ended March 31, 2017 Affected line item in the unaudited condensed consolidated statement of operations (Dollars in millions) Net actuarial loss associated with postretirement plans and workers’ compensation obligations: Postretirement health care and life insurance benefits $ (5.5 ) Net periodic benefit costs, excluding service cost Defined benefit pension plans (6.3 ) Net periodic benefit costs, excluding service cost Insignificant items 2.7 (9.1 ) Total before income taxes 3.3 Income tax benefit $ (5.8 ) Total after income taxes Prior service credit associated with postretirement plans: Postretirement health care and life insurance benefits $ 2.3 Net periodic benefit costs, excluding service cost Defined benefit pension plans (0.1 ) Net periodic benefit costs, excluding service cost 2.2 Total before income taxes (0.8 ) Income tax provision $ 1.4 Total after income taxes Cash flow hedges: Foreign currency cash flow hedge contracts $ (16.6 ) Operating costs and expenses Fuel and explosives commodity swaps (11.0 ) Operating costs and expenses Insignificant items (0.1 ) (27.7 ) Total before income taxes 9.1 Income tax benefit $ (18.6 ) Total after income taxes (1) Presented as gains (losses) in the unaudited condensed consolidated statements of operations.

Earnings per Share (EPS) (Table

Earnings per Share (EPS) (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings allocation method utilized in the calculation of basic and diluted EPS	The following illustrates the earnings allocation method utilized in the calculation of basic and diluted EPS. Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (In millions, except per share data) EPS numerator: Income from continuing operations, net of income taxes $ 208.3 $ 124.3 Less: Series A Convertible Preferred Stock dividends 102.5 — Less: Net (loss) income attributable to noncontrolling interests (2.1 ) 4.8 Income from continuing operations attributable to common stockholders, before allocation of earnings to participating securities 107.9 119.5 Less: Earnings allocated to participating securities 6.0 1.1 Income from continuing operations attributable to common stockholders, after allocation of earnings to participating securities (1) 101.9 118.4 Loss from discontinued operations, net of income taxes (1.3 ) (4.1 ) Less: Loss from discontinued operations allocated to participating securities (0.1 ) (0.1 ) Loss from discontinued operations attributable to common stockholders, after allocation of earnings to participating securities (1.2 ) (4.0 ) Net income attributable to common stockholders, after allocation of earnings to participating securities (1) $ 100.7 $ 114.4 EPS denominator: Weighted average shares outstanding — basic 120.9 18.3 Impact of dilutive securities 2.3 0.1 Weighted average shares outstanding — diluted (2) 123.2 18.4 Basic EPS attributable to common stockholders: Income from continuing operations $ 0.84 $ 6.46 Loss from discontinued operations (0.01 ) (0.22 ) Net income attributable to common stockholders $ 0.83 $ 6.24 Diluted EPS attributable to common stockholders: Income from continuing operations $ 0.83 $ 6.44 Loss from discontinued operations (0.01 ) (0.23 ) Net income attributable to common stockholders $ 0.82 $ 6.21 (1) The reallocation adjustment for participating securities to arrive at the numerator to calculate diluted EPS was $0.1 million for the three months ended March 31, 2018 and less than $0.1 million for the three months ended March 31, 2017. (2) The two-class method assumes that participating securities are not exercised or converted. As such, weighted average diluted shares outstanding excluded 8.4 million shares related to the participating securities for the three months ended March 31, 2018 .

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Reportable segment results	Reportable segment results were as follows: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Revenues: Powder River Basin Mining $ 389.3 $ 394.3 Midwestern U.S. Mining 201.7 193.2 Western U.S. Mining 143.7 149.7 Australian Metallurgical Mining 466.2 328.9 Australian Thermal Mining 201.4 224.8 Trading and Brokerage 20.1 15.0 Corporate and Other 40.3 20.3 Total $ 1,462.7 $ 1,326.2 Adjusted EBITDA: Powder River Basin Mining $ 74.5 $ 91.7 Midwestern U.S. Mining 31.2 50.0 Western U.S. Mining 32.0 50.0 Australian Metallurgical Mining 166.4 109.6 Australian Thermal Mining 61.6 75.6 Trading and Brokerage 1.2 8.8 Corporate and Other (1) (3.0 ) (44.4 ) Total $ 363.9 $ 341.3 (1)
Reconciliation of Adjusted EBITDA to consolidated loss from continuing operations, net of income taxes	A reconciliation of consolidated income from continuing operations, net of income taxes to Adjusted EBITDA follows: Successor Predecessor Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in millions) Income from continuing operations, net of income taxes $ 208.3 $ 124.3 Depreciation, depletion and amortization 169.6 119.9 Asset retirement obligation expenses 12.3 14.6 Asset impairment — 30.5 Changes in deferred tax asset valuation allowance and amortization of basis difference related to equity affiliates (7.6 ) (5.2 ) Interest expense 36.3 32.9 Interest income (7.2 ) (2.7 ) Reorganization items, net (12.8 ) 41.4 Unrealized gains on economic hedges (38.6 ) (16.6 ) Unrealized losses on non-coal trading derivative contracts 1.8 — Take-or-pay contract-based intangible recognition (8.3 ) — Income tax provisi on 10.1 2.2 Total Adjusted EBITDA $ 363.9 $ 341.3

Basis of Presentation - Textual

Basis of Presentation - Textuals (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Apr. 03, 2017
Successor
Fresh-Start Adjustment [Line Items]
Reorganization items, net	$ 12.8
Predecessor
Fresh-Start Adjustment [Line Items]
Reorganization items, net		$ (41.4)
Cash paid for “Reorganization items, net”		31.4
Voting shares received upon reorganization (less than 50%)			50.00%
Predecessor | Professional fee [Member]
Fresh-Start Adjustment [Line Items]
Reorganization items, net		(42.5)
Predecessor | accounts payable settlement (gains) losses [Member]
Fresh-Start Adjustment [Line Items]
Reorganization items, net		(0.7)
Predecessor | Interest Income [Member]
Fresh-Start Adjustment [Line Items]
Reorganization items, net		$ (0.4)

Newly Adopted Accounting Stan47

Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented - Adjustments Due to ASC 606 (Details) - Successor - USD ($) $ in Millions	Jan. 01, 2018	Mar. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investments and other assets		$ 343.6	$ 470.6
Adjustments due to ASU 2014-09		$ (22.5)
Investments and other assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investments and other assets	$ 448.1		470.6
Adjustments due to ASU 2014-09	(22.5)
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	591.1		$ 613.6
Adjustments due to ASU 2014-09	$ (22.5)

Newly Adopted Accounting Stan48

Newly Adopted Accounting Standards and Accounting Standards Not Yet Implemented - Adjustments Due to ASU 2017-07 (Details) - Predecessor $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating costs and expenses	$ 950.2
Selling and administrative expenses	36.3
Operating profit	212.5
Net periodic benefit costs, excluding service cost	(14.4)
Income from continuing operations before income taxes	126.5
Operating costs and expenses
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to ASU 2017-07	(13.5)
Selling and administrative expenses
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to ASU 2017-07	(0.9)
Operating profit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to ASU 2017-07	14.4
Net periodic benefit costs, excluding service cost
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to ASU 2017-07	14.4
Income from continuing operations before income taxes
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustments due to ASU 2017-07	0
Before Adoption [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating costs and expenses	963.7
Selling and administrative expenses	37.2
Operating profit	198.1
Net periodic benefit costs, excluding service cost	0
Income from continuing operations before income taxes	$ 126.5

Revenues - Accounts Receivable

Revenues - Accounts Receivable (Details) - Successor - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables, net	$ 388	$ 504.2
Miscellaneous receivables, net	136	47.9
Accounts receivable, net	$ 524	$ 552.1

Revenues - Revenue by Product T

Revenues - Revenue by Product Type and Market (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Disaggregation of Revenue [Line Items]
Revenues	$ 1,462.7
Successor | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	930.1
Successor | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	465.3
Successor | Other
Disaggregation of Revenue [Line Items]
Revenues	67.3
Successor | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	756.5
Successor | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	173.6
Successor | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	465.3
Successor | Operating Segments | Powder River Basin Mining
Disaggregation of Revenue [Line Items]
Revenues	389.3
Successor | Operating Segments | Powder River Basin Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	389.2
Successor | Operating Segments | Powder River Basin Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Powder River Basin Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.1
Successor | Operating Segments | Powder River Basin Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	389.2
Successor | Operating Segments | Powder River Basin Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Powder River Basin Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Midwestern U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues	201.7
Successor | Operating Segments | Midwestern U.S. Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	201.6
Successor | Operating Segments | Midwestern U.S. Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Midwestern U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.1
Successor | Operating Segments | Midwestern U.S. Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	200.9
Successor | Operating Segments | Midwestern U.S. Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0.7
Successor | Operating Segments | Midwestern U.S. Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Western U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues	143.7
Successor | Operating Segments | Western U.S. Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	138.3
Successor | Operating Segments | Western U.S. Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Western U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	5.4
Successor | Operating Segments | Western U.S. Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	130.3
Successor | Operating Segments | Western U.S. Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	8
Successor | Operating Segments | Western U.S. Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Australian Metallurgical Mining
Disaggregation of Revenue [Line Items]
Revenues	466.2
Successor | Operating Segments | Australian Metallurgical Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Australian Metallurgical Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	465.3
Successor | Operating Segments | Australian Metallurgical Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.9
Successor | Operating Segments | Australian Metallurgical Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Australian Metallurgical Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Australian Metallurgical Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	465.3
Successor | Operating Segments | Australian Thermal Mining
Disaggregation of Revenue [Line Items]
Revenues	201.4
Successor | Operating Segments | Australian Thermal Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	201
Successor | Operating Segments | Australian Thermal Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Operating Segments | Australian Thermal Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.4
Successor | Operating Segments | Australian Thermal Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	36.1
Successor | Operating Segments | Australian Thermal Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	164.9
Successor | Operating Segments | Australian Thermal Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage
Disaggregation of Revenue [Line Items]
Revenues	20.1
Successor | Corporate, Non-Segment | Trading and Brokerage | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage | Other
Disaggregation of Revenue [Line Items]
Revenues	20.1
Successor | Corporate, Non-Segment | Trading and Brokerage | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	40.3
Successor | Corporate, Non-Segment | Corporate and Other | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other | Other
Disaggregation of Revenue [Line Items]
Revenues	40.3
Successor | Corporate, Non-Segment | Corporate and Other | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues	$ 0
Predecessor
Disaggregation of Revenue [Line Items]
Revenues		$ 1,326.2
Predecessor | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		945.5
Predecessor | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		324.6
Predecessor | Other
Disaggregation of Revenue [Line Items]
Revenues		56.1
Predecessor | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		748.3
Predecessor | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		197.2
Predecessor | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		324.6
Predecessor | Operating Segments | Powder River Basin Mining
Disaggregation of Revenue [Line Items]
Revenues		394.3
Predecessor | Operating Segments | Powder River Basin Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		394.3
Predecessor | Operating Segments | Powder River Basin Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Powder River Basin Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Powder River Basin Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		394.3
Predecessor | Operating Segments | Powder River Basin Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Powder River Basin Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Midwestern U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues		193.2
Predecessor | Operating Segments | Midwestern U.S. Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		193.2
Predecessor | Operating Segments | Midwestern U.S. Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Midwestern U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Midwestern U.S. Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		193.2
Predecessor | Operating Segments | Midwestern U.S. Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Midwestern U.S. Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Western U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues		149.7
Predecessor | Operating Segments | Western U.S. Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		133.5
Predecessor | Operating Segments | Western U.S. Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Western U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		16.2
Predecessor | Operating Segments | Western U.S. Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		133.5
Predecessor | Operating Segments | Western U.S. Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Western U.S. Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Australian Metallurgical Mining
Disaggregation of Revenue [Line Items]
Revenues		328.9
Predecessor | Operating Segments | Australian Metallurgical Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Australian Metallurgical Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		324.6
Predecessor | Operating Segments | Australian Metallurgical Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		4.3
Predecessor | Operating Segments | Australian Metallurgical Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Australian Metallurgical Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Australian Metallurgical Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		324.6
Predecessor | Operating Segments | Australian Thermal Mining
Disaggregation of Revenue [Line Items]
Revenues		224.8
Predecessor | Operating Segments | Australian Thermal Mining | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		224.5
Predecessor | Operating Segments | Australian Thermal Mining | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Australian Thermal Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		0.3
Predecessor | Operating Segments | Australian Thermal Mining | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		27.3
Predecessor | Operating Segments | Australian Thermal Mining | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		197.2
Predecessor | Operating Segments | Australian Thermal Mining | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage
Disaggregation of Revenue [Line Items]
Revenues		15
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Other
Disaggregation of Revenue [Line Items]
Revenues		15
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues		20.3
Predecessor | Corporate, Non-Segment | Corporate and Other | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other | Other
Disaggregation of Revenue [Line Items]
Revenues		20.3
Predecessor | Corporate, Non-Segment | Corporate and Other | Domestic | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other | Export | Thermal coal
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other | Export | Metallurgical coal
Disaggregation of Revenue [Line Items]
Revenues		$ 0

Revenues - Revenues by Contract

Revenues - Revenues by Contract Duration (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Disaggregation of Revenue [Line Items]
Revenues	$ 1,462.7
Successor | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	488.1
Successor | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	745
Successor | Spot
Disaggregation of Revenue [Line Items]
Revenues	162.3
Successor | Other
Disaggregation of Revenue [Line Items]
Revenues	67.3
Successor | Operating Segments | Powder River Basin Mining
Disaggregation of Revenue [Line Items]
Revenues	389.3
Successor | Operating Segments | Powder River Basin Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	211.8
Successor | Operating Segments | Powder River Basin Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	131.6
Successor | Operating Segments | Powder River Basin Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues	45.8
Successor | Operating Segments | Powder River Basin Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.1
Successor | Operating Segments | Australian Thermal Mining
Disaggregation of Revenue [Line Items]
Revenues	201.4
Successor | Operating Segments | Australian Thermal Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	44.6
Successor | Operating Segments | Australian Thermal Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	132.7
Successor | Operating Segments | Australian Thermal Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues	23.7
Successor | Operating Segments | Australian Thermal Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.4
Successor | Operating Segments | Australian Metallurgical Mining
Disaggregation of Revenue [Line Items]
Revenues	466.2
Successor | Operating Segments | Australian Metallurgical Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	7.6
Successor | Operating Segments | Australian Metallurgical Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	389.9
Successor | Operating Segments | Australian Metallurgical Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues	67.8
Successor | Operating Segments | Australian Metallurgical Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.9
Successor | Operating Segments | Western U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues	143.7
Successor | Operating Segments | Western U.S. Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	117.7
Successor | Operating Segments | Western U.S. Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	9.6
Successor | Operating Segments | Western U.S. Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues	11
Successor | Operating Segments | Western U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	5.4
Successor | Operating Segments | Midwestern U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues	201.7
Successor | Operating Segments | Midwestern U.S. Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	106.4
Successor | Operating Segments | Midwestern U.S. Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	81.2
Successor | Operating Segments | Midwestern U.S. Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues	14
Successor | Operating Segments | Midwestern U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues	0.1
Successor | Corporate, Non-Segment | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	40.3
Successor | Corporate, Non-Segment | Corporate and Other | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other | Spot
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Corporate and Other | Other
Disaggregation of Revenue [Line Items]
Revenues	40.3
Successor | Corporate, Non-Segment | Trading and Brokerage
Disaggregation of Revenue [Line Items]
Revenues	20.1
Successor | Corporate, Non-Segment | Trading and Brokerage | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage | Spot
Disaggregation of Revenue [Line Items]
Revenues	0
Successor | Corporate, Non-Segment | Trading and Brokerage | Other
Disaggregation of Revenue [Line Items]
Revenues	$ 20.1
Predecessor
Disaggregation of Revenue [Line Items]
Revenues		$ 1,326.2
Predecessor | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		526.2
Predecessor | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		528.7
Predecessor | Spot
Disaggregation of Revenue [Line Items]
Revenues		215.2
Predecessor | Other
Disaggregation of Revenue [Line Items]
Revenues		56.1
Predecessor | Operating Segments | Powder River Basin Mining
Disaggregation of Revenue [Line Items]
Revenues		394.3
Predecessor | Operating Segments | Powder River Basin Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		238.5
Predecessor | Operating Segments | Powder River Basin Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		119.2
Predecessor | Operating Segments | Powder River Basin Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues		36.6
Predecessor | Operating Segments | Powder River Basin Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Australian Thermal Mining
Disaggregation of Revenue [Line Items]
Revenues		224.8
Predecessor | Operating Segments | Australian Thermal Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		33.4
Predecessor | Operating Segments | Australian Thermal Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		100.7
Predecessor | Operating Segments | Australian Thermal Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues		90.4
Predecessor | Operating Segments | Australian Thermal Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		0.3
Predecessor | Operating Segments | Australian Metallurgical Mining
Disaggregation of Revenue [Line Items]
Revenues		328.9
Predecessor | Operating Segments | Australian Metallurgical Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		4.9
Predecessor | Operating Segments | Australian Metallurgical Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		235.7
Predecessor | Operating Segments | Australian Metallurgical Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues		84
Predecessor | Operating Segments | Australian Metallurgical Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		4.3
Predecessor | Operating Segments | Western U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues		149.7
Predecessor | Operating Segments | Western U.S. Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		119.4
Predecessor | Operating Segments | Western U.S. Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		9.9
Predecessor | Operating Segments | Western U.S. Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues		4.2
Predecessor | Operating Segments | Western U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		16.2
Predecessor | Operating Segments | Midwestern U.S. Mining
Disaggregation of Revenue [Line Items]
Revenues		193.2
Predecessor | Operating Segments | Midwestern U.S. Mining | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		130
Predecessor | Operating Segments | Midwestern U.S. Mining | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		63.2
Predecessor | Operating Segments | Midwestern U.S. Mining | Spot
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Operating Segments | Midwestern U.S. Mining | Other
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues		20.3
Predecessor | Corporate, Non-Segment | Corporate and Other | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other | Spot
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Corporate and Other | Other
Disaggregation of Revenue [Line Items]
Revenues		20.3
Predecessor | Corporate, Non-Segment | Trading and Brokerage
Disaggregation of Revenue [Line Items]
Revenues		15
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Long-term contracts
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Short-term contracts
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Spot
Disaggregation of Revenue [Line Items]
Revenues		0
Predecessor | Corporate, Non-Segment | Trading and Brokerage | Other
Disaggregation of Revenue [Line Items]
Revenues		$ 15

Revenues - Textuals (Details)

Revenues - Textuals (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2019	Dec. 31, 2017
Successor
Disaggregation of Revenue [Line Items]
Interest Income	$ 2.1
Successor | Trade Accounts Receivable [Member]
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Accounts Receivable	0.5			$ 0.3
Provision for Doubtful Accounts	0.2
Long-term Investments and Receivables, Net	52.9			139.3
Successor | Miscellaneous Accounts Receivable [Member]
Disaggregation of Revenue [Line Items]
Allowance for Doubtful Accounts Receivable	$ 4.3			$ 4.3
Predecessor | Trade Accounts Receivable [Member]
Disaggregation of Revenue [Line Items]
Provision for Doubtful Accounts		$ 0
Scenario, Forecast | Long-term contracts
Disaggregation of Revenue [Line Items]
Deferred Revenue			$ 6,000
Deferred Revenue, Percentage of Total, Expected to be Recognized in Next Twelve Months			50.00%
Deferred Revenue, Percentage of Total, Expected to be Recognized Beyond Twelve Months			50.00%

Discontinued Operations - Loss,

Discontinued Operations - Loss, Assets and Liabilities of Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Successor
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations, net of income taxes	$ (1.3)
Successor | Discontinued Operations, Held-for-sale or Disposed of by Sale
Assets:
Other current assets	0.6
Total assets classified as discontinued operations	0.6
Liabilities:
Accounts payable and accrued expenses	70.7
Other noncurrent liabilities	170.6
Total liabilities classified as discontinued operations	$ 241.3
Predecessor
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations, net of income taxes		$ (4.1)
Predecessor | Discontinued Operations, Held-for-sale or Disposed of by Sale
Assets:
Other current assets			$ 0.3
Total assets classified as discontinued operations			0.3
Liabilities:
Accounts payable and accrued expenses			70.6
Other noncurrent liabilities			170
Total liabilities classified as discontinued operations			$ 240.6

Discontinued Operations - Patri

Discontinued Operations - Patriot Related Matters (Details) - Spinoff - Patriot - USD ($) $ in Millions	Jan. 25, 2017	Mar. 31, 2018	Dec. 31, 2007
Black Lung Occupational Disease Liability
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Initially Determined Potential Exposure from Patriot Bankruptcy			$ 150
Potential Exposure from Patriot Bankruptcy		$ 134.9
UMWA 1974 Pension Plan (UMWA Plan) Litigation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement of claim, amount awarded to other party	$ 75
Litigation settlement, liability		$ 47.4

Inventories - Schedule of Inven

Inventories - Schedule of Inventory (Details) - Successor - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Inventories [Line Items]
Materials and supplies	$ 103.1	$ 101.5
Raw coal	56.6	78.1
Saleable coal	105.8	111.7
Total	265.5	291.3
Reserve for materials and supplies
Inventories [Line Items]
Valuation Allowances and Reserves, Balance	$ 0.5	$ 0.6

Derivatives and Fair Value Me56

Derivatives and Fair Value Measurements - Gains and Losses on Hedging Derivatives (Details) - Designated as Hedging Instrument - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) realized in income on derivatives	$ (2.4)
Unrealized gain (loss) recognized in income on non- designated derivatives	(1.8)
Total loss recognized in income	(4.2)
Successor | Commodity swap contracts | Reorganization items, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) realized in income on derivatives	(2.4)
Unrealized gain (loss) recognized in income on non- designated derivatives	(1.8)
Total loss recognized in income	$ (4.2)
Predecessor
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from other comprehensive loss into income		$ (27.6)
Total loss recognized in income		(27.6)
Predecessor | Commodity swap contracts | Operating costs and expenses
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from other comprehensive loss into income		(11)
Total loss recognized in income		(11)
Predecessor | Foreign currency cash flow hedge contracts | Operating costs and expenses
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from other comprehensive loss into income		(16.6)
Total loss recognized in income		$ (16.6)

Derivatives and Fair Value Me57

Derivatives and Fair Value Measurements - Financial Instruments Measured on Recurring Basis (Details) - Successor - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Foreign currency cash flow hedge contracts
Derivative [Line Items]
Transfers Between Hierarchy Levels	$ 0
Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	2,300,000	$ 4,200,000
Fair Value, Measurements, Recurring | Foreign currency cash flow hedge contracts
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	2,300,000	4,200,000
Level 1 | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	0	0
Level 1 | Fair Value, Measurements, Recurring | Foreign currency cash flow hedge contracts
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	0	0
Level 2 | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	2,300,000	4,200,000
Level 2 | Fair Value, Measurements, Recurring | Foreign currency cash flow hedge contracts
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	2,300,000	4,200,000
Level 3 | Fair Value, Measurements, Recurring
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	0	0
Level 3 | Fair Value, Measurements, Recurring | Foreign currency cash flow hedge contracts
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 0	$ 0

Derivatives and Fair Value Me58

Derivatives and Fair Value Measurements - Long-term debt (Details) - Successor - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current and Long-term debt	$ 1,455.2	$ 1,460.8
Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Current and Long-term debt	$ 1,535.6	$ 1,547.4

Derivatives and Fair Value Me59

Derivatives and Fair Value Measurements - Texutals (Details) $ in Millions, $ in Millions	Dec. 31, 2018$ / $	Mar. 31, 2018AUD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Successor | Foreign currency forward contract
Derivatives, Fair Value [Line Items]
Derivative, notional amount		$ 1,125
Successor | Fair Value, Measurements, Recurring
Derivatives, Fair Value [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net			$ 2.3	$ 4.2
Successor | Fair Value, Measurements, Recurring | Foreign currency forward contract
Derivatives, Fair Value [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net			$ 2.3	$ 4.2
Scenario, Forecast | Lower rate | Foreign currency forward contract
Derivatives, Fair Value [Line Items]
Derivative, Exchange Rate Cap | $ / $	0.8150
Scenario, Forecast | Higher rate | Foreign currency forward contract
Derivatives, Fair Value [Line Items]
Derivative, Exchange Rate Cap | $ / $	0.82

Coal Trading - Trading Revenues

Coal Trading - Trading Revenues and Balance Sheet Offsetting (Details) - Coal Trading - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Cash Flow Hedging
Coal trading derivative instruments and balance sheet offsetting disclosures:
Net variation margin (held) posted		$ 0
Successor
Trading Revenues by Type of Instrument [Line Items]
Trading Revenues by Type of Instrument		20.1
Coal trading derivative instruments and balance sheet offsetting disclosures:
Assets from coal trading activities, gross amounts of recognized assets		53.6		$ 77.1
Liabilities from coal trading activities, gross amounts of recognized liabilities		(57.9)		(122)
Assets and (liabilities) from coal trading activities, net amounts recognized before the application of variation margin		(4.3)		(44.9)
Gross amounts of coal trading liabilities offset against associated coal trading assets		(42.4)		(74.5)
Gross amounts of coal trading assets offset against associated coal trading liabilities		42.4		74.5
Net coal trading (liabilities) assets offset against associated assets (liabilities)		0		0
Variation margin held offset against assets from coal trading activities	[1]	0		0
Variation margin posted offset against liabilities from coal trading activities	[1]	6.7		35.8
Net variation margin (held) posted	[1]	6.7		35.8
Assets from coal trading activities, net		11.2		2.6
Liabilities from coal trading activities, net		(8.8)		(11.7)
Net assets (liabilities) from coal trading activities		2.4		$ (9.1)
Successor | Futures, swaps and options
Trading Revenues by Type of Instrument [Line Items]
Trading Revenues by Type of Instrument		(16.9)
Successor | Physical purchase/sale contracts
Trading Revenues by Type of Instrument [Line Items]
Trading Revenues by Type of Instrument		$ 37
Predecessor
Trading Revenues by Type of Instrument [Line Items]
Trading Revenues by Type of Instrument			$ 15
Predecessor | Futures, swaps and options
Trading Revenues by Type of Instrument [Line Items]
Trading Revenues by Type of Instrument			(10.2)
Predecessor | Physical purchase/sale contracts
Trading Revenues by Type of Instrument [Line Items]
Trading Revenues by Type of Instrument			$ 25.2
[1]	None of the net variation margin posted at March 31, 2018 and December 31, 2017 related to cash flow hedges.

Coal Trading - Fair Value (Deta

Coal Trading - Fair Value (Details) - Coal Trading - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Successor | Fair Value, Measurements, Recurring
Fair value coal trading net assets (liabilities) measured on recurring basis:
Futures, swaps and options					$ 0.2	$ (7.2)
Physical purchase/sale contracts					2.2	(1.9)
Total net financial assets (liabilities)					2.4	(9.1)
Successor | Level 1 | Fair Value, Measurements, Recurring
Fair value coal trading net assets (liabilities) measured on recurring basis:
Futures, swaps and options					0.2	(3)
Physical purchase/sale contracts					0	0
Total net financial assets (liabilities)					0.2	(3)
Successor | Level 2 | Fair Value, Measurements, Recurring
Fair value coal trading net assets (liabilities) measured on recurring basis:
Futures, swaps and options					0	(4.2)
Physical purchase/sale contracts					2.2	(1.9)
Total net financial assets (liabilities)					2.2	(6.1)
Successor | Level 3 | Fair Value, Measurements, Recurring
Fair value coal trading net assets (liabilities) measured on recurring basis:
Futures, swaps and options					0	0
Physical purchase/sale contracts					0	0
Total net financial assets (liabilities)					$ 0	$ 0
Scenario, Forecast | Level 3
Fair value coal trading net assets (liabilities) measured on recurring basis:
Estimated Future Realization of Trading Portfolio	100.00%	(8.00%)	25.00%	83.00%

Coal Trading - Textuals (Detail

Coal Trading - Textuals (Details) $ in Millions		3 Months Ended
		Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)agency
Concentration Risk [Line Items]
Number of major credit rating agencies that adjusted corporate credit rating | agency			1
Coal Trading
Concentration Risk [Line Items]
Potential collateralization that may be requested by counterparties related to material adverse event		$ 1.1	$ 7
Collateral required to be posted to counterparties			0
External Credit Rating, Investment Grade [Member] | Credit Concentration Risk [Member] | Coal Trading Positions [Member] | Coal Trading
Concentration Risk [Line Items]
Concentration Risk, Percentage		55.00%
External Credit Rating, Non Investment Grade [Member] | Credit Concentration Risk [Member] | Coal Trading Positions [Member] | Coal Trading
Concentration Risk [Line Items]
Concentration Risk, Percentage		1.00%
Non Rated [Member] | Credit Concentration Risk [Member] | Coal Trading Positions [Member] | Coal Trading
Concentration Risk [Line Items]
Concentration Risk, Percentage		44.00%
Cash Flow Hedging | Coal Trading
Concentration Risk [Line Items]
Total asset (liabilities) from coal trading activities, net		$ 0
Successor | Coal Trading
Concentration Risk [Line Items]
Total asset (liabilities) from coal trading activities, net	[1]	6.7	35.8
Initial margin posted		18.5	18.8
Receivables from Brokers-Dealers and Clearing Organizations		4.6	$ 1.8
Additional potential collateral requirements for a credit downgrade		0
Margin posted to counterparties related to credit rating		$ 0
[1]	None of the net variation margin posted at March 31, 2018 and December 31, 2017 related to cash flow hedges.

Intangible Contract Assets an63

Intangible Contract Assets and Liabilities - Balances and Balance Sheet Classifications (Details) - Successor - Fresh Start Reporting - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fresh-Start Adjustment [Line Items]
Assets	$ 143.8	$ 177.2
Liabilities	119.7	133.4
Net Total	24.1	43.8
Take-or-pay contracts
Fresh-Start Adjustment [Line Items]
Assets	0	0
Coal supply agreements
Fresh-Start Adjustment [Line Items]
Assets	143.8	177.2
Net Total	105.2	134.5
Take-or-pay contracts
Fresh-Start Adjustment [Line Items]
Liabilities	81.1	90.7
Coal supply agreements
Fresh-Start Adjustment [Line Items]
Liabilities	(38.6)	(42.7)
Investments and other assets
Fresh-Start Adjustment [Line Items]
Assets	143.8	177.2
Liabilities	0	0
Net Total	143.8	177.2
Accounts payable and accrued expenses
Fresh-Start Adjustment [Line Items]
Assets	0	0
Liabilities	25.1	27.6
Other noncurrent liabilities
Fresh-Start Adjustment [Line Items]
Assets	0	0
Liabilities	$ 94.6	$ 105.8

Intangible Contract Assets an64

Intangible Contract Assets and Liabilities - Textuals (Details) - Fresh Start Reporting - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 03, 2017
Sales Contracts
Fresh-Start Adjustment [Line Items]
Intangible assets							$ 314.9
Liabilities							58.7
Intangible liabilities							$ 116.2
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of intangible assets and liabilities	$ 29.3
Take-or-pay contracts
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Intangible Liabilities	$ 8.3
Scenario, Forecast | Sales Contracts
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization, remainder of 2018						$ 68
Amortization, 2019					$ 27
Amortization, 2020				$ 8
Amortization, 2021			$ 3
Amortization, 2022		$ 1
Scenario, Forecast | Take-or-pay contracts
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of intangible liabilities, remainder of 2018						$ 19
Amortization of intangible liabilities, 2019					$ 18
Amortization of intangible liabilities, 2020				$ 9
Amortization of intangible liabilities, 2021			$ 4
Amortization of intangible liabilities, 2022		$ 3

Equity Method Investments - Tex

Equity Method Investments - Textuals (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Successor
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equity method investments and financing receivables	$ 72.3
Successor | Middlemount Mine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equity method investment, ownership percentage	50.00%
Successor | Financing Receivable | Middlemount Mine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, cash received from equity Interest	$ 35.8
Predecessor
Accounts, Notes, Loans and Financing Receivable [Line Items]
Equity method investments and financing receivables			$ 83.8
Predecessor | Financing Receivable | Middlemount Mine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, cash received from equity Interest		$ 31

Property, Plant, Equipment an66

Property, Plant, Equipment and Mine Development - Textuals (Details) - Successor - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Property, Plant, Equipment and Mine Development, Net [Line Items]
Land and coal interests	$ 3,891.7	$ 3,890.5
Buildings and improvements	452.3	470.6
Machinery and equipment	1,195.1	1,149.3
Less: Accumulated depreciation, depletion and amortization	(531.1)	(398.5)
Property, plant, equipment and mine development, net	$ 5,008	$ 5,111.9

Income Taxes - Textuals (Detail

Income Taxes - Textuals (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Income Taxes
Income tax provision	$ 10.1
Successor | Foreign Tax Authority
Income Taxes
Income tax provision	$ 0.5
Predecessor
Income Taxes
Income tax provision		$ 2.2
Predecessor | Foreign Tax Authority
Income Taxes
Income tax provision		$ 9.4

Long-term Debt - Schedule of De

Long-term Debt - Schedule of Debt (Details) - Successor - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Capital lease and other obligations	$ 67.8	$ 76
Less: Debt issuance costs	(56.9)	(59.4)
Total debt	1,455.2	1,460.8
Less: Current portion of long-term debt	87.1	42.1
Long-term debt	1,368.1	1,418.7
Senior Notes | 6.000% Senior Secured Notes due March 2022
Debt Instrument [Line Items]
Long-term debt	$ 500	$ 500
Stated interest rate	6.00%	6.00%
Senior Notes | 6.000% Senior Secured Notes due March 2022
Debt Instrument [Line Items]
Long-term debt	$ 500	$ 500
Stated interest rate	6.375%	6.375%
Term Loan | Senior Secured Term Loan due 2025
Debt Instrument [Line Items]
Long-term debt	$ 444.3	$ 444.2

Long-term Debt - Textuals (Deta

Long-term Debt - Textuals (Details)

Apr. 11, 2018USD ($)

Dec. 29, 2017USD ($)

Sep. 18, 2017USD ($)

Sep. 15, 2017USD ($)

Jul. 31, 2017USD ($)

Mar. 31, 2018USD ($)

Jun. 30, 2017USD ($)

Apr. 01, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2017USD ($)

Apr. 03, 2017USD ($)

Feb. 15, 2017USD ($)

Senior Notes | Effect of Plan | 6.000% Senior Secured Notes due March 2022

Debt Instrument [Line Items]

Principal amount

$ 500,000,000

Senior Notes | Effect of Plan | 6.000% Senior Secured Notes due March 2022

Debt Instrument [Line Items]

Principal amount

$ 500,000,000

Term Loan | Successor Credit Agreement

Debt Instrument [Line Items]

Restricted payments threshold

$ 50,000,000

$ 450,000,000

Debt Instrument, Restricted Payments Basket

$ 450,000,000

Debt Instrument, Covenant, Fixed Charge Coverage Ratio

2.25

2

Term Loan | Successor Credit Agreement | Subsequent Event

Debt Instrument [Line Items]

Debt Instrument, Fee Amount

$ 2,000,000

Payment for Debt Extinguishment or Debt Prepayment Cost

$ 46,000,000

Term Loan | Successor Credit Agreement | Total Leverage Ration Less Or Equal 2.00 to 1.00

Debt Instrument [Line Items]

Total Leverage Ratio

2

Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal 1.25 to 1.00

Debt Instrument [Line Items]

Total Leverage Ratio

1.25

Dividend payment and stock purchase payment threshold

$ 25,000,000

Term Loan | Effect of Plan | Successor Credit Agreement

Debt Instrument [Line Items]

Principal amount

$ 950,000,000

Successor

Debt Instrument [Line Items]

Debt issuance cost

56,900,000

$ 59,400,000

Interest expense

36,300,000

Capital lease obligations

67,800,000

76,000,000

Successor | Revolving Credit Facility | 2017 Revolver

Debt Instrument [Line Items]

Debt issuance cost

4,700,000

Interest expense

$ 1,800,000

Line of Credit Facility, Maximum Borrowing Capacity

350,000,000

Unrestricted Cash Netting Limit

800,000,000

Revolving Credit Facility, Fee on Unused Borrowings

0.50%

Aggregate Letters of Credit, Maximum

$ 163,100,000

Successor | Revolving Credit Facility | 2017 Revolver | Total Leverage Ration Less Or Equal 2.00 to 1.00

Debt Instrument [Line Items]

Total Leverage Ratio

2

Successor | Revolving Credit Facility | 2017 Revolver | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Basis spread on variable rate

2.75%

3.25%

Successor | Revolving Credit Facility | Letter of Credit

Debt Instrument [Line Items]

Debt Instrument, Base Interest Rate

3.375%

Successor | Senior Notes | 6.000% Senior Secured Notes due March 2022

Debt Instrument [Line Items]

Stated interest rate

6.00%

6.00%

Long-term debt

$ 500,000,000

$ 500,000,000

Successor | Senior Notes | 6.000% Senior Secured Notes due March 2022 | Debt Instrument, Redemption, Period One

Debt Instrument [Line Items]

Redemption price, percentage

103.00%

Successor | Senior Notes | 6.000% Senior Secured Notes due March 2022 | Debt Instrument, Redemption, Period Two

Debt Instrument [Line Items]

Redemption price, percentage

101.50%

Successor | Senior Notes | 6.000% Senior Secured Notes due March 2022

Debt Instrument [Line Items]

Stated interest rate

6.375%

6.375%

Long-term debt

$ 500,000,000

$ 500,000,000

Successor | Senior Notes | 6.000% Senior Secured Notes due March 2022 | Debt Instrument, Redemption, Period One

Debt Instrument [Line Items]

Redemption price, percentage

104.80%

Successor | Senior Notes | 6.000% Senior Secured Notes due March 2022 | Debt Instrument, Redemption, Period Two

Debt Instrument [Line Items]

Redemption price, percentage

103.20%

Successor | Senior Notes | 6.000% Senior Secured Notes due March 2022 | Debt Instrument, Redemption, Period Three

Debt Instrument [Line Items]

Redemption price, percentage

101.60%

Successor | Senior Notes | 6.00% And 6.375% Senior Secured Notes, Successor Notes

Debt Instrument [Line Items]

Debt issuance cost

$ 49,500,000

Interest expense

$ 17,500,000

Successor | Senior Notes | 6.00% And 6.375% Senior Secured Notes, Successor Notes | Domestic

Debt Instrument [Line Items]

Collateral, capital stock, percent

100.00%

Successor | Senior Notes | 6.00% And 6.375% Senior Secured Notes, Successor Notes | Export

Debt Instrument [Line Items]

Collateral, non-voting capital stock, percent

100.00%

Collateral, voting capital stock, percent

65.00%

Successor | Senior Notes | 6.00% And 6.375% Senior Secured Notes, Successor Notes | Peabody Investments (Gibraltar) Limited

Debt Instrument [Line Items]

Collateral, non-voting capital stock, percent

100.00%

Collateral, voting capital stock, percent

65.00%

Successor | Term Loan | Successor Credit Agreement

Debt Instrument [Line Items]

Interest expense

$ 6,600,000

Principal amount

450,000,000

Original issue discount and deferred finance costs

$ 37,300,000

Mandatory principal prepayment, percent of excess cash flow

75.00%

Mandatory principal prepayment, if required, period payable, threshold

100 days

Excess proceeds from sales of assets, threshold ($10 million or greater)

$ 10,000,000

Payment for Debt Extinguishment or Debt Prepayment Cost

$ 200,000,000

$ 500,000,000

$ 150,000,000

Successor | Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00

Debt Instrument [Line Items]

Mandatory principal prepayment, percent of excess cash flow

50.00%

Successor | Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00 | Maximum

Debt Instrument [Line Items]

Total Leverage Ratio

2

Successor | Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00 | Minimum

Debt Instrument [Line Items]

Total Leverage Ratio

1.50

Successor | Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00

Debt Instrument [Line Items]

Mandatory principal prepayment, percent of excess cash flow

25.00%

Successor | Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00 | Maximum

Debt Instrument [Line Items]

Total Leverage Ratio

1.50

Successor | Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00 | Minimum

Debt Instrument [Line Items]

Total Leverage Ratio

1

Successor | Term Loan | Successor Credit Agreement | Total Leverage Ratio Less or Equal to 1.00 to 1.00

Debt Instrument [Line Items]

Mandatory principal prepayment, percent of excess cash flow

0.00%

Total Leverage Ratio

1

Successor | Term Loan | Successor Credit Agreement | London Interbank Offered Rate (LIBOR)

Debt Instrument [Line Items]

Basis spread on variable rate

3.50%

3.50%

4.50%

Floor interest rate

1.00%

1.00%

1.00%

Successor | Term Loan | Senior Secured Term Loan due 2025

Debt Instrument [Line Items]

Long-term debt

$ 444,300,000

$ 444,200,000

Secured Debt

950,000,000

Successor | Line of Credit | 2017 Revolver | Revolving Credit Facility

Debt Instrument [Line Items]

Long-term debt

$ 350,000,000

Predecessor

Debt Instrument [Line Items]

Interest expense, adequate protection payments

$ 29,800,000

Contractual interest expense

$ 92,900,000

Interest expense

$ 32,900,000

Pension and Postretirement Be70

Pension and Postretirement Benefit Costs (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Apr. 02, 2017plan
Successor
Components of net periodic benefit cost
Net periodic pension (benefit) cost	$ 4.5
Successor | Defined benefit pension plans
Components of net periodic benefit cost
Service cost for benefits earned	0.6
Interest cost on projected benefit obligation	7.8
Expected return on plan assets	(10.7)
Amortization of prior service cost and net actuarial loss	0
Net periodic pension (benefit) cost	$ (2.3)
Other Defined Benefit Plan Information [Abstract]
Funding threshold	80.00%
Number of non-qualified pension plans prior to reorganization | plan			2
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 30
Successor | Postretirement benefit plans
Components of net periodic benefit cost
Service cost for benefits earned	2
Interest cost on projected benefit obligation	7.1
Amortization of prior service cost and net actuarial loss	0
Net periodic pension (benefit) cost	$ 9.1
Predecessor
Components of net periodic benefit cost
Net periodic pension (benefit) cost		$ 14.4
Predecessor | Defined benefit pension plans
Components of net periodic benefit cost
Service cost for benefits earned		0.6
Interest cost on projected benefit obligation		9.7
Expected return on plan assets		(11)
Amortization of prior service cost and net actuarial loss		6.4
Net periodic pension (benefit) cost		5.7
Predecessor | Postretirement benefit plans
Components of net periodic benefit cost
Service cost for benefits earned		2.3
Interest cost on projected benefit obligation		8.4
Amortization of prior service cost and net actuarial loss		3.2
Net periodic pension (benefit) cost		$ 13.9

Accumulated Other Comprehensi71

Accumulated Other Comprehensive Income - Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Successor
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign Currency Translation Adjustment	$ (0.8)
Successor | Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), foreign currency translation adjustment, net of tax, beginning of period	1.4
Foreign Currency Translation Adjustment	(0.8)
Accumulated other comprehensive income (loss), foreign currency translation adjustment, net of tax, end of period	0.6
Successor | Total Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign Currency Translation Adjustment	(0.8)
Accumulated other comprehensive income, beginning of period	1.4
Accumulated other comprehensive income (loss), current period change, net of tax	(0.8)
Accumulated other comprehensive income, end of period	$ 0.6
Predecessor
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign Currency Translation Adjustment		$ 5.5

Accumulated Other Comprehensi72

Accumulated Other Comprehensive Income - Reclassification from AOCI (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Successor
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating costs and expenses		$ (1,057.2)
Net periodic benefit costs, excluding service cost		4.5
Selling and administrative expenses		(37)
Income tax benefit (provision)		(10.1)
Total after income taxes		208.3
Successor | Defined benefit pension plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net periodic benefit costs, excluding service cost		$ (2.3)
Predecessor
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating costs and expenses			$ (950.2)
Net periodic benefit costs, excluding service cost			14.4
Selling and administrative expenses			(36.3)
Income tax benefit (provision)			(2.2)
Total after income taxes			124.3
Predecessor | Reclassification out of Accumulated Other Comprehensive Income | Net actuarial loss associated with postretirement plans and workers' compensation obligations
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Insignificant items	[1]		2.7
Total before income taxes	[1]		(9.1)
Income tax benefit (provision)	[1]		3.3
Total after income taxes	[1]		(5.8)
Predecessor | Reclassification out of Accumulated Other Comprehensive Income | Prior service credit associated with postretirement plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Total before income taxes	[1]		2.2
Income tax benefit (provision)	[1]		(0.8)
Total after income taxes	[1]		1.4
Predecessor | Reclassification out of Accumulated Other Comprehensive Income | Cash flow hedges
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Total before income taxes			(27.7)
Income tax benefit (provision)	[1]		9.1
Total after income taxes			(18.6)
Predecessor | Reclassification out of Accumulated Other Comprehensive Income | Foreign currency cash flow hedge contracts | Cash flow hedges
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating costs and expenses	[1]		(16.6)
Predecessor | Reclassification out of Accumulated Other Comprehensive Income | Fuel and explosives commodity swaps | Cash flow hedges
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating costs and expenses	[1]		(11)
Predecessor | Reclassification out of Accumulated Other Comprehensive Income | Insignificant items | Cash flow hedges
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Insignificant items	[1]		(0.1)
Predecessor | Postretirement health care and life insurance benefits | Reclassification out of Accumulated Other Comprehensive Income | Net actuarial loss associated with postretirement plans and workers' compensation obligations
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net periodic benefit costs, excluding service cost			5.5
Predecessor | Postretirement health care and life insurance benefits | Reclassification out of Accumulated Other Comprehensive Income | Prior service credit associated with postretirement plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net periodic benefit costs, excluding service cost	[1]		(2.3)
Predecessor | Defined benefit pension plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net periodic benefit costs, excluding service cost			5.7
Predecessor | Defined benefit pension plans | Reclassification out of Accumulated Other Comprehensive Income | Net actuarial loss associated with postretirement plans and workers' compensation obligations
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net periodic benefit costs, excluding service cost			6.3
Predecessor | Defined benefit pension plans | Reclassification out of Accumulated Other Comprehensive Income | Prior service credit associated with postretirement plans
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net periodic benefit costs, excluding service cost	[1]		$ 0.1
[1]	Presented as gains (losses) in the unaudited condensed consolidated statements of operations.

Other Events (Details)

Other Events (Details) $ in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018AUD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Feb. 06, 2018
Successor
Other Commercial Events [Line Items]
Proceeds from disposal of assets, net of notes receivable		$ 23
Net gain on disposal of assets		30.6
Asset Impairment Charges		0
Successor | Contract Termination [Member]
Other Commercial Events [Line Items]
Asset Impairment Charges		0
Successor | Red Mountain Joint Venture
Other Commercial Events [Line Items]
Proceeds from disposal of assets, net of notes receivable		20
Net gain on disposal of assets		7.1
Successor | Queensland’s Bowen Basin [Member]
Other Commercial Events [Line Items]
Proceeds from disposal of assets, net of notes receivable	$ 37
Net gain on disposal of assets		$ 20.6
Successor | DTA and PBGC
Other Commercial Events [Line Items]
Equity method investment, ownership percentage				50.00%
Predecessor
Other Commercial Events [Line Items]
Proceeds from disposal of assets, net of notes receivable			$ 24.3
Net gain on disposal of assets			22.8
Asset Impairment Charges			30.5
Predecessor | Contract Termination [Member]
Other Commercial Events [Line Items]
Asset Impairment Charges			$ 30.5
Predecessor | DTA and PBGC
Other Commercial Events [Line Items]
Equity method investment, ownership percentage			37.50%
Proceeds from disposal of assets, net of notes receivable			$ 20.5
Net gain on disposal of assets			$ 19.7

Earnings per Share (EPS) (Detai

Earnings per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Jan. 31, 2018	Dec. 31, 2017
Successor
EPS numerator:
Income from continuing operations, net of income taxes		$ 208.3
Less: Series A Convertible Preferred Stock dividends		102.5
Less: Net (loss) income attributable to noncontrolling interests		(2.1)
Income from continuing operations attributable to common stockholders, before allocation of earnings to participating securities		107.9
Less: Earnings allocated to participating securities		6
Income from continuing operations attributable to common stockholders, after allocation of earnings to participating securities (1)	[1]	101.9
Loss from discontinued operations, net of income taxes		(1.3)
Less: Loss from discontinued operations allocated to participating securities		(0.1)
Loss from discontinued operations attributable to common stockholders, after allocation of earnings to participating securities		(1.2)
Net income attributable to common stockholders, after allocation of earnings to participating securities (1)	[1]	$ 100.7
EPS denominator:
Weighted average shares outstanding — basic		120.9
Impact of dilutive securities		2.3
Weighted average shares outstanding — diluted	[2]	123.2
Basic EPS attributable to common stockholders:
Income from continuing operations, per basic share		$ 0.84
Loss from discontinued operation, per basic share		(0.01)
Basic income per share (in dollars per share)		0.83
Diluted EPS attributable to common stockholders:
Income from continuing operations, per diluted share		0.83
Loss from discontinued operations, per diluted share		(0.01)
Diluted income per share (in dollars per share)		$ 0.82
Earnings Per Share Table Footnotes [Abstract]
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted		$ 0.1
Weighted Average Number of Shares Outstanding, Diluted		8.4
Antidilutive shares excluded from EPS calculation (less than 0.1 million for the period April 2 through June 30, 2017)		0.1
Successor | Convertible Preferred Stock
Earnings Per Share Table Footnotes [Abstract]
Preferred stock, shares issued		0		30	30
Successor | Common Stock | Common Stock
Earnings Per Share Table Footnotes [Abstract]
Common stock, shares converted from convertible preferred stock				59.3
Predecessor
EPS numerator:
Income from continuing operations, net of income taxes			$ 124.3
Less: Series A Convertible Preferred Stock dividends			0
Less: Net (loss) income attributable to noncontrolling interests			4.8
Income from continuing operations attributable to common stockholders, before allocation of earnings to participating securities			119.5
Less: Earnings allocated to participating securities			1.1
Income from continuing operations attributable to common stockholders, after allocation of earnings to participating securities (1)	[1]		118.4
Loss from discontinued operations, net of income taxes			(4.1)
Less: Loss from discontinued operations allocated to participating securities			(0.1)
Loss from discontinued operations attributable to common stockholders, after allocation of earnings to participating securities			(4)
Net income attributable to common stockholders, after allocation of earnings to participating securities (1)	[1]		$ 114.4
EPS denominator:
Weighted average shares outstanding — basic			18.3
Impact of dilutive securities			0.1
Weighted average shares outstanding — diluted	[2]		18.4
Basic EPS attributable to common stockholders:
Income from continuing operations, per basic share			$ 6.46
Loss from discontinued operation, per basic share			(0.22)
Basic income per share (in dollars per share)			6.24
Diluted EPS attributable to common stockholders:
Income from continuing operations, per diluted share			6.44
Loss from discontinued operations, per diluted share			(0.23)
Diluted income per share (in dollars per share)			$ 6.21
Earnings Per Share Table Footnotes [Abstract]
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted			$ 0.1
Antidilutive shares excluded from EPS calculation (less than 0.1 million for the period April 2 through June 30, 2017)			0.2
[1]	The reallocation adjustment for participating securities to arrive at the numerator to calculate diluted EPS was $0.1 million for the three months ended March 31, 2018 and less than $0.1 million for the
[2]	The two-class method assumes that participating securities are not exercised or converted. As such, weighted average diluted shares outstanding excluded 8.4 million shares related to the participating securities for the three months ended March 31, 2018.

Financial Instruments and Oth75

Financial Instruments and Other Guarantees - Textuals (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Apr. 03, 2017
Successor
Guarantee Obligations [Line Items]
Asset retirement obligations	$ 665.9		$ 657
Letters of credit outstanding, amount	0
Interest expense	36.3
Collateral arrangements - current	109.1		0
Collateral arrangements	0		323.1
Net impact on collateral requirements	214
Restricted cash			$ 40.1
Successor | Secured Debt | Accounts Receivable Securitization Program, April 3, 2020
Guarantee Obligations [Line Items]
Letters of credit drawn on, amount	176.3
Line of Credit Facility, Maximum Borrowing Capacity				$ 250
Cash collateral required	0
Interest expense	1.3
Successor | U.S Mining
Guarantee Obligations [Line Items]
Asset retirement obligations	469
Surety Bonds outstanding for reclamation	1,074.3
Letters of credit outstanding, amount	174.1
Successor | Australian Mining
Guarantee Obligations [Line Items]
Asset retirement obligations	230.2
Surety Bonds outstanding for reclamation	270.1
Letters of credit outstanding, amount	14.4
Cash collateral in support of reclamation obligations or activities	$ 99.7
Predecessor
Guarantee Obligations [Line Items]
Interest expense		$ 32.9
Net impact on collateral requirements		(66.4)
Predecessor | Secured Debt | Accounts Receivable Securitization Program, April 3, 2020
Guarantee Obligations [Line Items]
Interest expense		$ 2

Commitments and Contingencies -

Commitments and Contingencies - Commitments (Details) - Successor - Capital Addition Purchase Commitments $ in Millions	Mar. 31, 2018USD ($)
Long-term Purchase Commitment [Line Items]
Unrecorded Unconditional Purchase Obligation	$ 190.1
Purchase commitments for capital expenditures	$ 140.7

Commitments and Contingencies77

Commitments and Contingencies - Contingencies (Details) - 3 months ended Mar. 31, 2018 $ in Millions, $ in Millions	AUD ($)defendant	USD ($)
Monto Coal Pty Limited
Loss Contingency [Abstract]
Ownership Percentage In Subsidiaries		51.00%
Number of defendants | defendant	3
Minimum | Monto Coal Pty Limited
Loss Contingency [Abstract]
Damages sought, value	$ 15.6
Maximum | Monto Coal Pty Limited
Loss Contingency [Abstract]
Damages sought, value	$ 1,800
Berenergy Corporation vs. the Company | Berenergy
Loss Contingency [Abstract]
Loss contingency accrual		$ 13.1

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Successor
Reportable segment results
Revenues		$ 1,462.7
Total Adjusted EBITDA		363.9
Net gain on disposal of assets		30.6
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Income from continuing operations, net of income taxes		208.3
Depreciation, depletion and amortization		169.6
Asset retirement obligation expenses		12.3
Asset impairment		0
Changes in deferred tax asset valuation allowance and amortization of basis difference related to equity affiliates		(7.6)
Interest expense		36.3
Interest income		(7.2)
Reorganization items, net		(12.8)
Unrealized gains on economic hedges		(38.6)
Unrealized losses on non-coal trading derivative contracts		1.8
Take-or-pay contract-based intangible recognition		(8.3)
Income tax provision		10.1
Total Adjusted EBITDA		363.9
Successor | Red Mountain Joint Venture
Reportable segment results
Net gain on disposal of assets		7.1
Successor | Iffley Land Transaction [Member]
Reportable segment results
Net gain on disposal of assets		20.6
Successor | Powder River Basin Mining | Operating Segments
Reportable segment results
Revenues		389.3
Total Adjusted EBITDA		74.5
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA		74.5
Successor | Midwestern U.S. Mining | Operating Segments
Reportable segment results
Revenues		201.7
Total Adjusted EBITDA		31.2
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA		31.2
Successor | Western U.S. Mining | Operating Segments
Reportable segment results
Revenues		143.7
Total Adjusted EBITDA		32
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA		32
Successor | Australian Metallurgical Mining | Operating Segments
Reportable segment results
Revenues		466.2
Total Adjusted EBITDA		166.4
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA		166.4
Successor | Australian Thermal Mining | Operating Segments
Reportable segment results
Revenues		201.4
Total Adjusted EBITDA		61.6
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA		61.6
Successor | Trading and Brokerage | Corporate, Non-Segment
Reportable segment results
Revenues		20.1
Total Adjusted EBITDA		1.2
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA		1.2
Successor | Corporate and Other | Corporate, Non-Segment
Reportable segment results
Revenues		40.3
Total Adjusted EBITDA	[1]	(3)
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA	[1]	$ (3)
Predecessor
Reportable segment results
Revenues			$ 1,326.2
Total Adjusted EBITDA			341.3
Net gain on disposal of assets			22.8
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Income from continuing operations, net of income taxes			124.3
Depreciation, depletion and amortization			119.9
Asset retirement obligation expenses			14.6
Asset impairment			30.5
Changes in deferred tax asset valuation allowance and amortization of basis difference related to equity affiliates			(5.2)
Interest expense			32.9
Interest income			(2.7)
Reorganization items, net			41.4
Unrealized gains on economic hedges			(16.6)
Unrealized losses on non-coal trading derivative contracts			0
Take-or-pay contract-based intangible recognition			0
Income tax provision			2.2
Total Adjusted EBITDA			341.3
Predecessor | DTA and PBGC
Reportable segment results
Net gain on disposal of assets			19.7
Predecessor | Powder River Basin Mining | Operating Segments
Reportable segment results
Revenues			394.3
Total Adjusted EBITDA			91.7
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA			91.7
Predecessor | Midwestern U.S. Mining | Operating Segments
Reportable segment results
Revenues			193.2
Total Adjusted EBITDA			50
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA			50
Predecessor | Western U.S. Mining | Operating Segments
Reportable segment results
Revenues			149.7
Total Adjusted EBITDA			50
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA			50
Predecessor | Australian Metallurgical Mining | Operating Segments
Reportable segment results
Revenues			328.9
Total Adjusted EBITDA			109.6
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA			109.6
Predecessor | Australian Thermal Mining | Operating Segments
Reportable segment results
Revenues			224.8
Total Adjusted EBITDA			75.6
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA			75.6
Predecessor | Trading and Brokerage | Corporate, Non-Segment
Reportable segment results
Revenues			15
Total Adjusted EBITDA			8.8
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA			8.8
Predecessor | Corporate and Other | Corporate, Non-Segment
Reportable segment results
Revenues			20.3
Total Adjusted EBITDA	[1]		(44.4)
Reconciliation Of Adjusted EBITDA To Consolidated Loss From Continuing Operations, Net of Income Taxes [Abstract]
Total Adjusted EBITDA	[1]		$ (44.4)
[1]	Includes the gain of $20.6 million on the sale of certain surplus land assets in Queensland and the gain of $7.1 million recognized on the sale of the Company’s interest in the RMJV during the three months ended March 31, 2018 and the gain of $19.7 million recognized on the sale of Dominion Terminal Associates during the three months ended March 31, 2017, as described in Note 15. “Other Events”.