Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues	$ 2,937,119us-gaap_CoalProductsAndServicesRevenue	$ 3,014,357us-gaap_CoalProductsAndServicesRevenue	$ 3,768,126us-gaap_CoalProductsAndServicesRevenue
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)	2,566,193	2,663,136	3,155,099
Depreciation, depletion and amortization	418,748	426,442	492,211
Amortization of acquired sales contracts, net	(13,187)	(9,457)	(25,189)
Change in fair value of coal derivatives and coal trading activities, net	(3,686)	7,845	(16,590)
Asset impairment and mine closure costs	24,113	220,879	539,182
Goodwill impairment	0us-gaap_GoodwillImpairmentLoss	265,423us-gaap_GoodwillImpairmentLoss	330,680us-gaap_GoodwillImpairmentLoss
Contract settlement resulting from Patriot Coal bankruptcy	0us-gaap_GainLossOnContractTermination	0us-gaap_GainLossOnContractTermination	(58,335)us-gaap_GainLossOnContractTermination
Reduction in accrual related to acquired litigation		0us-gaap_LossContingencyLossInPeriod	(79,532)us-gaap_LossContingencyLossInPeriod
Selling, general and administrative expenses	114,223	133,448	134,299
Other operating income, net	(19,754)us-gaap_OtherOperatingIncomeExpenseNet	(30,218)us-gaap_OtherOperatingIncomeExpenseNet	(63,357)us-gaap_OtherOperatingIncomeExpenseNet
Total operating expenses	3,086,650us-gaap_OperatingExpenses	3,677,498us-gaap_OperatingExpenses	4,525,138us-gaap_OperatingExpenses
Loss from operations	(149,531)us-gaap_OperatingIncomeLoss	(663,141)us-gaap_OperatingIncomeLoss	(757,012)us-gaap_OperatingIncomeLoss
Interest expense, net
Interest expense	(390,946)us-gaap_InterestExpense	(381,267)us-gaap_InterestExpense	(317,615)us-gaap_InterestExpense
Interest and investment income	7,758us-gaap_OtherNonoperatingIncome	6,603us-gaap_OtherNonoperatingIncome	5,473us-gaap_OtherNonoperatingIncome
Interest expense, net	(383,188)	(374,664)	(312,142)
Nonoperating expense
Net loss resulting from early retirement and refinancing of debt	0	(42,921)	(23,668)
Loss from continuing operations before income taxes	(532,719)	(1,080,726)	(1,092,822)
Provision for (benefit from) income taxes	25,634us-gaap_IncomeTaxExpenseBenefit	(335,498)us-gaap_IncomeTaxExpenseBenefit	(353,907)us-gaap_IncomeTaxExpenseBenefit
Loss from continuing operations	(558,353)	(745,228)	(738,915)
Income from discontinued operations, including gain on sale - net of tax	0	103,396	55,228
Net income (loss)	(558,353)us-gaap_ProfitLoss	(641,832)us-gaap_ProfitLoss	(683,687)us-gaap_ProfitLoss
Less: Net income attributable to noncontrolling interest		0	(268)
Net loss attributable to Arch Coal, Inc.	$ (558,353)us-gaap_NetIncomeLoss	$ (641,832)us-gaap_NetIncomeLoss	$ (683,955)us-gaap_NetIncomeLoss
Losses per common share
Basic and diluted LPS- Loss from continuing operations	$ (2.63)	$ (3.52)	$ (3.50)
Basic and diluted LPS - Net loss	$ (2.63)us-gaap_EarningsPerShareBasicAndDiluted	$ (3.03)us-gaap_EarningsPerShareBasicAndDiluted	$ (3.24)us-gaap_EarningsPerShareBasicAndDiluted
Weighted average shares outstanding
Basic and diluted weighted average shares outstanding	212,221	212,098	211,381
Dividends declared per common share	$ 0.01	$ 0.12	$ 0.20

Aggregate net gain and losses (whether realized or unrealized) related to trading activities whether or not settled physically and the net unrealized gains and losses on coal derivative instruments not designated as hedging instruments recognized in earnings in the period.

No definition available.