Arch Resources (ARCH) 10-Q 12 May 14 2014 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 30, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'ARCH COAL INC	'
Entity Central Index Key	'0001037676	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	212,279,999

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]	'	'
Revenues	$735,971	$737,370
Costs, expenses and other operating[Abstract]	'	'
Cost of sales (exclusive of items shown separately below)	686,314	649,743
Depreciation, depletion and amortization	104,423	110,193
Amortization of acquired sales contracts, net	-3,696	-2,810
Change in fair value of coal derivatives and coal trading activities, net	914	1,308
Selling, general and administrative expenses	29,136	33,209
Other operating income, net	-7,998	-2,842
Total operating expenses	809,093	788,801
Loss from operations	-73,122	-51,431
Interest expense, net	'	'
Interest expense	-96,471	-95,074
Interest and investment income	1,843	2,836
Interest expense, net	-94,628	-92,238
Loss from continuing operations before income taxes	-167,750	-143,669
Benefit from income taxes	-43,611	-59,353
Loss from continuing operations	-124,139	-84,316
Income from discontinued operations, net of tax	0	14,267
Net loss	($124,139)	($70,049)
Loss from continuing operations	'	'
Basic and diluted loss per common share (usd per share)	($0.59)	($0.40)
Net loss	'	'
Diluted loss per common share (usd per share)	($0.59)	($0.33)
Basic and diluted weighted average shares outstanding	212,171	212,062
Dividends declared per common share	$0.01	$0.03

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Loss) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'
Net loss	($124,139)	($70,049)
Derivative instruments	'	'
Comprehensive loss before tax	-229	-1,179
Income tax benefit	82	425
Derivatives Qualifying as Hedges, Adjustment, Net of Tax	-147	-754
Pension, postretirement and other post-employment benefits	'	'
Comprehensive income (loss) before tax	-1,847	1,954
Income tax benefit (provision)	665	-703
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	-1,182	1,251
Available-for-sale securities	'	'
Comprehensive income (loss) before tax	-2,033	1,553
Income tax benefit (provision)	732	-559
Available-for-sale Securities Adjustment, Net of Tax	-1,301	994
Total other comprehensive income (loss)	-2,630	1,491
Total comprehensive loss	($126,769)	($68,558)

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$865,761	$911,099
Short term investments	248,572	248,414
Trade accounts receivable	230,002	198,020
Other receivables	44,810	31,553
Inventories	224,806	264,161
Prepaid royalties	6,896	8,083
Deferred income taxes	48,869	49,144
Coal derivative assets	12,316	14,851
Other current assets	55,296	56,746
Total current assets	1,737,328	1,782,071
Property, plant and equipment, net	6,616,144	6,734,286
Other assets	'	'
Prepaid royalties	87,552	87,577
Equity investments	223,235	221,456
Other noncurrent assets	158,925	164,803
Total other assets	469,712	473,836
Total assets	8,823,184	8,990,193
Current liabilities	'	'
Accounts payable	160,361	176,142
Accrued expenses and other current liabilities	328,561	278,587
Current maturities of debt	29,950	33,493
Total current liabilities	518,872	488,222
Long-term debt	5,112,995	5,118,002
Asset retirement obligations	390,408	402,713
Accrued pension benefits	10,484	7,111
Accrued postretirement benefits other than pension	37,995	39,255
Accrued workers’ compensation	75,817	78,062
Deferred income taxes	368,057	413,546
Other noncurrent liabilities	181,866	190,033
Total liabilities	6,696,494	6,736,944
Stockholders' equity	'	'
Common stock, $0.01 par value, authorized 260,000 shares, issued 213,792 shares at both March 31, 2014 and December 31, 2013.	2,141	2,141
Paid-in capital	3,040,946	3,038,613
Treasury stock, at cost	-53,848	-53,848
Accumulated deficit	-897,611	-771,349
Accumulated other comprehensive income	35,062	37,692
Total stockholders’ equity	2,126,690	2,253,249
Total liabilities and stockholders’ equity	$8,823,184	$8,990,193

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]	'	'
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	260,000,000	260,000,000
Common stock, shares issued	213,792,000	213,792,000

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activties	'	'
Net loss	($124,139)	($70,049)
Adjustments to reconcile net loss to cash provided by (used in) operating activities:	'	'
Depreciation, depletion and amortization	104,423	118,868
Amortization of acquired sales contracts, net	-3,696	-2,810
Amortization relating to financing activities	3,236	6,167
Prepaid royalties expensed	1,803	3,537
Employee stock-based compensation expense	2,333	2,713
Gains on disposals and divestitures, net	-15,129	-595
Changes in:	'	'
Receivables	-27,245	-12,340
Inventories	7,441	-2,816
Accounts payable, accrued expenses and other current liabilities	43,989	38,249
Income taxes, net	-115	458
Deferred income taxes	-43,698	-54,993
Other	10,522	16,902
Cash provided by (used in) operating activities	-40,275	43,291
Investing activities	'	'
Capital expenditures	-14,454	-54,522
Additions to prepaid royalties	-591	-9,142
Proceeds from disposals and divestitures	28,195	714
Purchases of short term investments	-119,176	-26,787
Proceeds from sales of short term investments	117,681	11,534
Investments in and advances to affiliates	-3,242	-4,298
Change in restricted cash	0	1,163
Cash provided by (used in) investing activities	8,413	-81,338
Financing activities	'	'
Payments on term loan	-4,875	-4,125
Net payments on other debt	-4,521	-5,964
Debt financing costs	-1,957	'
Dividends paid	-2,123	-6,367
Cash used in financing activities	-13,476	-16,456
Decrease in cash and cash equivalents	-45,338	-54,503
Cash and cash equivalents, beginning of period	911,099	784,622
Cash and cash equivalents, end of period	$865,761	$730,119

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements include the accounts of Arch Coal, Inc. and its subsidiaries and controlled entities (the “Company”). The Company’s primary business is the production of thermal and metallurgical coal from surface and underground mines located throughout the United States, for sale to utility, industrial and steel producers both in the United States and around the world. The Company currently operates mining complexes in West Virginia, Kentucky, Maryland, Virginia, Illinois, Wyoming and Colorado. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation.
	The Company completed the sale of Canyon Fuel Company, LLC ("Canyon Fuel") on August 16, 2013. The results of Canyon Fuel have been segregated from continuing operations and are reflected, net of tax, as discontinued operations in the condensed consolidated statements of operations for the three months ended March 31, 2013.
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three months ended March 31, 2014 are not necessarily indicative of results to be expected for the year ending December 31, 2014. These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.

Accounting_Policies

Accounting Policies	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Accounting Policies	'
	Accounting Policies
	There is no new accounting guidance that is expected to have a significant impact on the Company’s financial statements.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Abstract]	'
Accumulated Other Comprehensive Income	'
	Accumulated Other Comprehensive Income
	The following items are included in accumulated other comprehensive income:
						Pension,
						Postretirement
						and Other								Accumulated
						Post-								Other
		Derivative				Employment				Available-for-				Comprehensive
		Instruments				Benefits				Sale Securities				Loss
		(In thousands)
	Balance at December 31, 2013	$	565			$	31,112			$	6,015			$	37,692
	Unrealized gains (losses)	47				—				(1,657		)		(1,610		)
	Amounts reclassified from accumulated other comprehensive income	(194		)		(1,182		)		356				(1,020		)
	Balance at March 31, 2014	$	418			$	29,930			$	4,714			$	35,062
	The following amounts were reclassified out of accumulated other comprehensive income:
			Amount Reclassified from
			Accumulated other comprehensive income										Line Item in the
	Details about accumulated other		Three months ended March 31,										Condensed Consolidated
	comprehensive income components		2014				2013						Statement of Operations
			(In thousands)
	Derivative instruments		$	303			$	859					Revenues
			(109		)		(309		)				Benefit from income taxes
			$	194			$	550					Net of tax
	Pension, postretirement and other post-employment benefits
	Amortization of prior service credits		$	2,626			$	2,908		1		1
	Amortization of actuarial gains (losses), net		(779		)		(4,862		)	1		1
			1,847				(1,954		)
			(665		)		703						Benefit from income taxes
			$	1,182			$	(1,251	)				Net of tax
	Available-for-sale securities		$	(556	)		$	(59	)	2		2	Interest and investment income
			200				21						Benefit from income taxes
			$	(356	)		$	(38	)				Net of tax
	1 Production-related benefits and workers' compensation costs are included in inventoriable production costs.
	2 The gains and losses on sales of available-for-sale-securities are determined on a specific identification basis.

Divestitures

Divestitures	3 Months Ended
	Mar. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Divestitures	'
	Divestitures
	During the first quarter of 2014, the Company entered into agreements to sell an operating thermal coal complex and an idled thermal coal mine in Kentucky and the Company's ADDCAR subsidiary, which manufactures a patented highwall mining system. The sales closed during the quarter for total consideration of $45.5 million. The Company received $26.3 million in cash and the remaining $19.0 million is payable $8.0 million on June 30, 2014 and $11.0 million on December 31, 2014. The Company recognized a net pre-tax gain of $13.8 million from these divestitures, reflected in "other operating income, net" in the condensed consolidated statement of operations.
	The following table summarizes the assets and liabilities of the divested operations reflected in the December 31, 2013 consolidated balance sheet:
		(in thousands)
	Inventories	$	33,283
	Other current assets	1,032
	Net property, plant & equipment	104,587
	Other noncurrent assets	139
	Accounts payable and accrued expenses	13,005
	Other noncurrent liabilities	24,276
	The following table summarizes the results of Canyon Fuel, reflected as discontinued operations in the condensed consolidated statement of operations through the date of disposition:
			Three Months Ended March 31, 2013
		(in thousands)
	Total revenues		$	88,132
	Income from discontinued operations before income taxes		$	18,989
	Less: income tax expense		4,722
	Income from discontinued operations		$	14,267
	Basic and diluted earnings per common share from discontinued operations		$	0.07

Inventories

Inventories	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories consist of the following:
		March 31,		31-Dec
		2014		2013
		(In thousands)
	Coal	$	98,125	$	117,531
	Repair parts and supplies	126,681		137,497
	Work-in-process	—		9,133
		$	224,806	$	264,161
	The repair parts and supplies are stated net of an allowance for slow-moving and obsolete inventories of $8.6 million at March 31, 2014 and $8.4 million at December 31, 2013.

Investments_in_AvailableforSal

Investments in Available-for-Sale Securities	3 Months Ended
	Mar. 31, 2014
Available-for-sale Securities [Abstract]	'
Investments in Available-for-Sale Securities	'
	Investments in Available-for-Sale Securities
	The Company has invested in marketable debt securities, primarily highly liquid AA - rated corporate bonds and U.S. government and government agency securities. These investments are held in the custody of a major financial institution. These securities, along with the Company's investments in marketable equity securities, are classified as available-for-sale securities and, accordingly, the unrealized gains and losses are recorded through other comprehensive income.
	The Company's investments in available-for-sale marketable securities are as follows:
		March 31, 2014
											Balance Sheet
				Gross		Gross					Classification
				Unrealized		Unrealized			Fair		Short-Term		Other
		Cost Basis		Gains		Losses			Value		Investments		Assets
		(In thousands)
	Available-for-sale:
	Corporate notes and bonds	$	250,723	$	4	$	(2,155	)	$	248,572	$	248,572	$	—
	Equity securities	5,420		12,203		(2,698		)	14,925		—		14,925
	Total Investments	$	256,143	$	12,207	$	(4,853	)	$	263,497	$	248,572	$	14,925
		December 31, 2013
											Balance Sheet
				Gross		Gross					Classification
				Unrealized		Unrealized			Fair		Short-Term		Other
		Cost Basis		Gains		Losses			Value		Investments		Assets
		(In thousands)
	Available-for-sale:
	U.S. government and agency securities	$	65,002	$	11	$	(75	)	$	64,938	$	64,938	$	—
	Corporate notes and bonds	184,773		7		(1,304		)	183,476		183,476		—
	Equity securities	5,271		13,660		(2,902		)	16,029		—		16,029
	Total Investments	$	255,046	$	13,678	$	(4,281	)	$	264,443	$	248,414	$	16,029
	The aggregate fair value of investments with unrealized losses that have been owned for less than a year was $200.4 million and $164.3 million at March 31, 2014 and December 31, 2013, respectively. The aggregate fair value of investments with unrealized losses that were owned for over a year, and were also in a continuous unrealized loss position during that time, was $34.7 million and $48.7 million at March 31, 2014 and December 31, 2013, respectively.
	The debt securities outstanding at March 31, 2014 have maturity dates ranging from the second quarter of 2014 through the third quarter of 2015. The Company classifies its investments as current based on the nature of the investments and their availability to provide cash for use in current operations.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivatives	'
	Derivatives
	Diesel fuel price risk management
	The Company is exposed to price risk with respect to diesel fuel purchased for use in its operations. The Company anticipates purchasing approximately 57 to 67 million gallons of diesel fuel for use in its operations during 2014. To protect the Company’s cash flows from increases in the price of diesel fuel for its operations, the Company uses forward physical diesel purchase contracts and purchased heating oil call options. At March 31, 2014, the Company had protected the price of approximately 87% of its expected purchases for the remainder of 2014 and 30% of its expected purchases during the first half of 2015. At March 31, 2014, the Company had purchased heating oil call options for approximately 61 million gallons for the purpose of managing the price risk associated with future diesel purchases.
	The Company has also purchased heating oil call options to manage the price risk associated with fuel surcharges on its barge and rail shipments, which cover increases in diesel fuel prices for the respective carriers. At March 31, 2014, the Company held heating oil call options for 3.8 million gallons that will settle ratably in the remainder of 2014 for the purpose of managing the fluctuations in cash flows associated with fuel surcharges on future shipments.
	These positions reduce the Company’s risk of cash flow fluctuations related to these surcharges but the positions are not accounted for as hedges.
	Coal price risk management positions
	The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market in order to manage its exposure to coal prices. The Company has exposure to the risk of fluctuating coal prices related to forecasted sales or purchases of coal or to the risk of changes in the fair value of a fixed price physical sales contract. Certain derivative contracts may be designated as hedges of these risks.
	At March 31, 2014, the Company held derivatives for risk management purposes that are expected to settle in the following years:
	(Tons in thousands)		2014			2015			Total
	Coal sales		3,991			1,380			5,371
	Coal purchases		1,778			—			1,778
	The Company has also entered into a nominal quantity of natural gas put options to protect the Company from decreases in natural gas prices, which could impact coal demand. These options are not accounted for as hedges.
	Coal trading positions
	The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market for trading purposes. The Company is exposed to the risk of changes in coal prices on the value of its coal trading portfolio. The estimated future realization of the value of the trading portfolio is $6.6 million of gains during the remainder of 2014 and $1.4 million of gains in 2015.
	Tabular derivatives disclosures
	The Company has master netting agreements with all of its counterparties which allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. Such netting arrangements reduce the Company’s credit exposure related to these counterparties. For classification purposes, the Company records the net fair value of all the positions with a given counterparty as a net asset or liability in the condensed consolidated balance sheets. The amounts shown in the table below represent the fair value position of individual contracts, and not the net position presented in the accompanying condensed consolidated balance sheets. The fair value and location of derivatives reflected in the accompanying condensed consolidated balance sheets are as follows:
			31-Mar-14											31-Dec-13
	Fair Value of Derivatives		Asset				Liability							Asset			Liability
	(In thousands)		Derivative				Derivative							Derivative			Derivative
	Derivatives Designated as Hedging Instruments
	Coal		$	1,101			$	(215	)					$	909		$	(26	)
	Derivatives Not Designated as Hedging Instruments
	Heating oil -- diesel purchases		2,683				—							4,681			—
	Heating oil -- fuel surcharges		152				—							422			—
	Coal -- held for trading purposes		75,886				(67,944		)					55,327			(45,763		)
	Coal -- risk management		4,543				(1,453		)					6,342			(1,950		)
	Natural gas		398				—							—			—
	Total		83,662				(69,397		)					66,772			(47,713		)
	Total derivatives		84,763				(69,612		)					67,681			(47,739		)
	Effect of counterparty netting		(69,612		)		69,612							(47,727		)	47,727
	Net derivatives as classified in the balance sheets		$	15,151			$	—			$	15,151		$	19,954		$	(12	)	$	19,942
					31-Mar-14				31-Dec-13
	Net derivatives as reflected on the balance sheets				2835
	Heating oil		Other current assets		$	2,835			$	5,103
	Coal		Coal derivative assets		12,316				14,851
			Accrued expenses and other current liabilities		—				(12		)
					$	15,151			$	19,942
	The Company had a current asset for the right to reclaim cash collateral of $6.5 million at March 31, 2014 and $2.2 million at December 31, 2013. These amounts are not included with the derivatives presented in the table above and are included in “other current assets” in the accompanying condensed consolidated balance sheets.
	The effects of derivatives on measures of financial performance are as follows:
	Derivatives used in Cash Flow Hedging Relationships (in thousands)
	For the Three Months Ended March 31,
			Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)								Gains (Losses) Reclassified from Other Comprehensive Income into Income
											(Effective Portion)
			2014				2013				2014			2013
	Coal sales	(1)	$	(515	)		$	(176	)		$	706		$	1,221
	Coal purchases	(2)	589				(182		)		(404		)	(362		)
	Totals		$	74			$	(358	)		$	302		$	859
	No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the three month periods ended March 31, 2014 and 2013.
	Derivatives Not Designated as Hedging Instruments (in thousands)
	For the Three Months Ended March 31,
			Gain (Loss) Recognized
			2014				2013
	Coal — unrealized	(3)	$	(1,302	)		$	1,470
	Coal — realized	(4)	$	2,879			$	9,217
	Natural gas  — unrealized	(3)	$	8			$	—
	Heating oil — diesel purchases	(4)	$	(2,963	)		$	(4,261	)
	Heating oil — fuel surcharges	(4)	$	(254	)		$	(565	)
	____________________________________________________________
	Location in statement of operations:
	(1) — Revenues
	(2) — Cost of sales
	(3) — Change in fair value of coal derivatives and coal trading activities, net
	(4) — Other operating income, net
The Company recognized net unrealized and realized gains of $0.4 million during the three months ended March 31, 2014 and net unrealized and realized losses of $2.8 million during the three months ended March 31, 2013 related to its trading portfolio, which are included in the caption “Change in fair value of coal derivatives and coal trading activities, net” in the accompanying condensed consolidated statements of operations, and are not included in the previous tables reflecting the effects of derivatives on measures of financial performance.
Based on fair values at March 31, 2014, gains on derivative contracts designated as hedge instruments in cash flow hedges of approximately $0.9 million are expected to be reclassified from other comprehensive income into earnings during the next twelve months.

Accrued_Expenses_and_Other_Cur

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 2014
Accrued Expenses and Other Current Liabilities [Abstract]	'
Accrued Expenses and Other Current Liabilities	'
	Accrued Expenses and Other Current Liabilities
	Accrued expenses and other current liabilities consist of the following:
		March 31,		December 31,
		2014		2013
		(In thousands)
	Payroll and employee benefits	$	58,220	$	67,621
	Taxes other than income taxes	112,406		114,664
	Interest	79,731		18,528
	Acquired sales contracts	14,439		14,373
	Workers’ compensation	16,470		12,434
	Asset retirement obligations	22,682		24,940
	Other	24,613		26,027
		$	328,561	$	278,587

Debt_and_Financing_Arrangement

Debt and Financing Arrangements	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Debt and Financing Arrangements	'
	Debt and Financing Arrangements
		March 31,		December 31,
		2014		2013
		(In thousands)
	Term loan due 2018 ($1.92 billion and $1.93 billion face value, respectively)	$	1,902,731	$	1,906,975
	7.00% senior notes due 2019 at par	1,000,000		1,000,000
	9.875% senior notes due 2019 ($375.0 million face value)	362,573		362,358
	8.00% senior secured notes due 2019 at par	350,000		350,000
	7.25% senior notes due 2020 at par	500,000		500,000
	7.25% senior notes due 2021 at par	1,000,000		1,000,000
	Other	27,641		32,162
		5,142,945		5,151,495
	Less current maturities of debt	29,950		33,493
	Long-term debt	$	5,112,995	$	5,118,002
	At March 31, 2014, the available borrowing capacity under the Company's lines of credit was approximately $250.1 million.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income taxes
	During the three months ended March 31, 2014, the Company determined it was more likely than not that a portion of the federal and state net operating losses it expects to generate in 2014 will not be realized through future taxable income, and the estimated annual effective rate includes a valuation allowance for that portion. In applying the estimated annual effective rate to earnings for the three months ended March 31, 2014, the Company increased its valuation allowance by $21.6 million related to federal net operating losses and $2.2 million related to state net operating losses.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Fair Value Measurements
	The hierarchy of fair value measurements assigns a level to fair value measurements based on the inputs used in the respective valuation techniques. The levels of the hierarchy, as defined below, give the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs.
	·    Level 1 is defined as observable inputs such as quoted prices in active markets for identical assets. Level 1 assets include available-for-sale equity securities, U.S. Treasury securities, and coal futures that are submitted for clearing on the New York Mercantile Exchange.
	·    Level 2 is defined as observable inputs other than Level 1 prices. These include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s level 2 assets and liabilities include U.S. government agency securities and commodity contracts (coal and heating oil) with fair values derived from quoted prices in over-the-counter markets or from prices received from direct broker quotes.
	·    Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. These include the Company’s commodity option contracts (coal, natural gas and heating oil) valued using modeling techniques, such as Black-Scholes, that require the use of inputs, particularly volatility, that are rarely observable. Changes in the unobservable inputs would not have a significant impact on the reported Level 3 fair values at March 31, 2014.
	The table below sets forth, by level, the Company’s financial assets and liabilities that are recorded at fair value in the accompanying condensed consolidated balance sheet:
		31-Mar-14
		Total			Level 1		Level 2		Level 3
		(In thousands)
	Assets:
	Investments in marketable securities	$	263,497		$	14,925	$	248,572	$	—
	Derivatives	15,151			10,956		218		3,977
	Total assets	$	278,648		$	25,881	$	248,790	$	3,977
	The Company’s contracts with its counterparties allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. For classification purposes, the Company records the net fair value of all the positions with these counterparties as a net asset or liability. Each level in the table above displays the underlying contracts according to their classification in the accompanying condensed consolidated balance sheet, based on this counterparty netting.
	The following table summarizes the change in the fair values of financial instruments categorized as level 3.
		Three Months Ended March 31, 2014
		(In thousands)
	Balance, beginning of period	$	4,946
	Realized and unrealized losses recognized in earnings, net	(2,925		)
	Purchases	1,956
	Ending balance	$	3,977
	Net unrealized losses of $2.6 million were recognized during the three months ended March 31, 2014 related to level 3 financial instruments held on March 31, 2014.
	Fair Value of Long-Term Debt
	At March 31, 2014 and December 31, 2013, the fair value of the Company’s debt, including amounts classified as current, was $4.5 billion and $4.6 billion, respectively. Fair values are based upon observed prices in an active market, when available, or from valuation models using market information, which fall into Level 2 in the fair value hierarchy.

Loss_Per_Common_Share

Loss Per Common Share	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Loss Per Common Share	'
	Loss Per Common Share
	The effect of options, restricted stock and restricted stock units equaling 6.9 million and 8.6 million shares of common stock were excluded from the calculation of diluted weighted average shares outstanding for the three month periods ended March 31, 2014 and 2013, respectively, because the exercise price or grant price of the securities exceeded the average market price of the Company's common stock for these periods. The weighted average share impacts of options, restricted stock and restricted stock units that were excluded from the calculation of weighted average shares due to the Company's incurring a net loss for the three months ended March 31, 2014 and 2013 were not significant.

Employee_Benefit_Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2014
Pension and Other Postretirement Benefit Expense [Abstract]	'
Employee Benefit Plans	'
	Employee Benefit Plans
	The following table details the components of pension benefit costs (credits):
		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Service cost	$	5,924		$	7,700
	Interest cost	4,364			3,926
	Expected return on plan assets	(5,978		)	(5,806		)
	Amortization of prior service costs (credits)	(54		)	(158		)
	Amortization of other actuarial losses	948			4,551
	Net benefit cost	$	5,204		$	10,213
	The following table details the components of other postretirement benefit costs (credits):
		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Service cost	$	444		$	556
	Interest cost	464			431
	Amortization of prior service credits	(2,501		)	(2,750		)
	Amortization of other actuarial losses (gains)	(170		)	77
	Net benefit credit	$	(1,763	)	$	(1,686	)

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	The Company accrues for cost related to contingencies when a loss is probable and the amount is reasonably determinable. Disclosure of contingencies is included in the financial statements when it is at least reasonably possible that a material loss or an additional material loss in excess of amounts already accrued may be incurred.
	Allegheny Energy Supply (“Allegheny”), the sole customer of coal produced at the Company's subsidiary Wolf Run Mining Company's (“Wolf Run”) Sycamore No. 2 mine, filed a lawsuit against Wolf Run, Hunter Ridge Holdings, Inc. (“Hunter Ridge”), and ICG in state court in Allegheny County, Pennsylvania on December 28, 2006, and amended its complaint on April 23, 2007. Allegheny claimed that Wolf Run breached a coal supply contract when it declared force majeure under the contract upon idling the Sycamore No. 2 mine in the third quarter of 2006, and that Wolf Run continued to breach the contract by failing to ship in volumes referenced in the contract.  The Sycamore No. 2 mine was idled after encountering adverse geologic conditions and abandoned gas wells that were previously unidentified and unmapped.
	After extensive searching for gas wells and rehabilitation of the mine, it was re-opened in 2007, but with notice to Allegheny that it would necessarily operate at reduced volumes in order to safely and effectively avoid the many gas wells within the reserve.  The amended complaint also alleged that the production stoppages constitute a breach of the guarantee agreement by Hunter Ridge and breach of certain representations made upon entering into the contract in early 2005.  Allegheny voluntarily dropped the breach of representation claims later.  Allegheny claimed that it would incur costs in excess of $100 million to purchase replacement coal over the life of the contract.  ICG, Wolf Run and Hunter Ridge answered the amended complaint on August 13, 2007, disputing all of the remaining claims.
	On November 3, 2008, ICG, Wolf Run and Hunter Ridge filed an amended answer and counterclaim against the plaintiffs seeking to void the coal supply agreement due to, among other things, fraudulent inducement and conspiracy.  On September 23, 2009, Allegheny filed a second amended complaint alleging several alternative theories of liability in its effort to extend contractual liability to ICG, which was not a party to the original contract and did not exist at the time Wolf Run and Allegheny entered into the contract.  No new substantive claims were asserted.  ICG answered the second amended complaint on October 13, 2009, denying all of the new claims.  The Company's counterclaim was dismissed on motion for summary judgment entered on May 11, 2010.  Allegheny's claims against ICG were also dismissed by summary judgment, but the claims against Wolf Run and Hunter Ridge were not.  The court conducted a non-jury trial of this matter beginning on January 10, 2011 and concluding on February 1, 2011.
	At the trial, Allegheny presented its evidence for breach of contract and claimed that it is entitled to past and future damages in the aggregate of between $228 million and $377 million.  Wolf Run and Hunter Ridge presented their defense of the claims, including evidence with respect to the existence of force majeure conditions and excuse under the contract and applicable law.  Wolf Run and Hunter Ridge presented evidence that Allegheny's damages calculations were significantly inflated because it did not seek to determine damages as of the time of the breach and in some instances artificially assumed future nondelivery or did not take into account the apparent requirement to supply coal in the future.  On May 2, 2011, the trial court entered a Memorandum and Verdict determining that Wolf Run had breached the coal supply contract and that the performance shortfall was not excused by force majeure.  The trial court awarded total damages and interest in the amount of $104.1 million, which consisted of $13.8 million for past damages, and $90.3 million for future damages.  ICG and Allegheny filed post-verdict motions in the trial court and on August 23, 2011, the court denied the parties' motions.  The court entered a final judgment on August 25, 2011, in the amount of $104.1 million, which included pre-judgment interest.
	The parties appealed the lower court's decision to the Superior Court of Pennsylvania.  On August 13, 2012, the Superior Court of Pennsylvania affirmed the award of past damages, but ruled that the lower court should have calculated future damages as of the date of breach, and remanded the matter back to the lower court with instructions to recalculate that portion of the award. On November 19, 2012, Allegheny filed a Petition for Allowance of Appeal with the Supreme Court of Pennsylvania and Wolf Run and Hunter Ridge filed an Answer. On July 2, 2013, the Supreme Court of Pennsylvania denied the Petition of Allowance. As this action finalized the past damage award, Wolf Run paid $15.6 million for the past damage amount, including interest, to Allegheny in July 2013. The future damage award is now back before the lower court, and a new trial has been scheduled to start May 13, 2014.
	In addition, the Company is a party to numerous claims and lawsuits with respect to various matters. As of March 31, 2014 and December 31, 2013, the Company had accrued $23.1 million and $30.4 million, respectively, for all legal matters, including $10.1 million and $11.7 million, respectively, classified as current.  The ultimate resolution of any such legal matter could result in outcomes which may be materially different from amounts the Company has accrued for such matters.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	The Company's reportable business segments are based on the major coal producing basins in which the Company operates and may include a number of mine complexes. The Company manages its coal sales by coal basin, not by individual mining complex. Geology, coal transportation routes to customers, regulatory environments and coal quality or type are characteristic to a basin, and, accordingly, market and contract pricing have developed by coal basin. Mining operations are evaluated based on their per-ton operating costs (defined as including all mining costs but excluding pass-through transportation expenses), as well as on other non-financial measures, such as safety and environmental performance. The Company’s reportable segments are the Powder River Basin (PRB) segment, with operations in Wyoming; and the Appalachia (APP) segment, with operations in West Virginia, Kentucky, Maryland and Virginia.  The “Other” category combines other operating segments and includes the Company’s coal mining operations in Colorado and Illinois and its ADDCAR subsidiary, which the Company sold in the first quarter of 2014.
	Operating segment results for the three months ended March 31, 2014 and 2013 are presented below. Results for the reportable segments include all direct costs of mining, including all depreciation, depletion and amortization related to the mining operations, even if the assets are not recorded at the operating segment level. These reportable segments results do not reflect the mine closure or impairment costs, since those are not reflected in the operating income reviewed by management. Corporate, Other and Eliminations includes these charges, as well as the change in fair value of coal derivatives and coal trading activities, net; corporate overhead; land management; other support functions; and the elimination of intercompany transactions. The operating segment results reflect only those from continuing operations, and exclude the results of Canyon Fuel, since they are classified as discontinued operations in the condensed consolidated statements of operations.
	The asset amounts below represent an allocation of assets consistent with the basis used for the Company’s incentive compensation plans. The amounts in Corporate, Other and Eliminations represent primarily corporate assets (cash, receivables, investments, plant, property and equipment) as well as unassigned coal reserves, above-market acquired sales contracts and other unassigned assets.
		PRB			APP			Other		Corporate,			Consolidated
								Operating		Other and
								Segments		Eliminations
		(in thousands)
	Three Months Ended March 31, 2014
	Revenues	$	358,607		$	279,137		$	98,227	$	—		$	735,971
	Income (loss) from operations	(4,898		)	(25,728		)	1,635		(44,131		)	(73,122		)
	Depreciation, depletion and amortization	39,245			54,988			9,519		671			104,423
	Amortization of acquired sales contracts, net	(789		)	(2,974		)	67		—			(3,696		)
	Capital expenditures	2,094			8,156			1,801		2,403			14,454
	Three Months Ended March 31, 2013
	Revenues	$	361,946		$	282,618		$	92,806	$	—		$	737,370
	Income (loss) from operations	15,516			(27,116		)	7,384		(47,215		)	(51,431		)
	Depreciation, depletion and amortization	42,227			55,331			11,304		1,331			110,193
	Amortization of acquired sales contracts, net	(1,199		)	(2,472		)	861		—			(2,810		)
	Capital expenditures	2,157			49,297			763		2,305			54,522
	A reconciliation of segment income (loss) from operations to consolidated loss before income taxes follows:
		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Loss from operations	$	(73,122	)	$	(51,431	)
	Interest expense	(96,471		)	(95,074		)
	Interest and investment income	1,843			2,836
	Loss from continuing operations before income taxes	$	(167,750	)	$	(143,669	)

Supplemental_Condensed_Consoli

Supplemental Condensed Consolidating Financial Information	3 Months Ended
	Mar. 31, 2014
Supplemental Condensed Consolidating Financial Information [Abstract]	'
Supplemental Condensed Consolidating Financial Information	'
	Supplemental Consolidating Financial Information
	Pursuant to the indentures governing Arch Coal, Inc.’s senior notes, certain wholly-owned subsidiaries of the Company have fully and unconditionally guaranteed the senior notes on a joint and several basis. The following tables present condensed consolidating financial information for (i) the Company, (ii) the issuer of the senior notes, (iii) the guarantors under the senior notes, and (iv) the entities which are not guarantors under the senior notes (Arch Receivable Company, LLC and the Company’s subsidiaries outside the United States):
	Condensed Consolidating Statements of Operations
	Three Months Ended March 31, 2014
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	735,971		$	—		$	—		$	735,971
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	3,389			683,775			—			(850		)	686,314
	Depreciation, depletion and amortization	1,472			102,942			9			—			104,423
	Amortization of acquired sales contracts, net	—			(3,696		)	—			—			(3,696		)
	Change in fair value of coal derivatives and coal trading activities, net	—			914			—			—			914
	Selling, general and administrative expenses	19,944			7,865			1,803			(476		)	29,136
	Other operating income, net	1,593			(9,480		)	(1,437		)	1,326			(7,998		)
		26,398			782,320			375			—			809,093
	Loss from investment in subsidiaries	(35,347		)	—			—			35,347			—
	Loss from operations	(61,745		)	(46,349		)	(375		)	35,347			(73,122		)
	Interest expense, net
	Interest expense	(113,655		)	(6,324		)	(1,050		)	24,558			(96,471		)
	Interest and investment income	7,601			17,651			1,149			(24,558		)	1,843
		(106,054		)	11,327			99			—			(94,628		)
	Loss from continuing operations before income taxes	(167,799		)	(35,022		)	(276		)	35,347			(167,750		)
	Provision for (benefit from) income taxes	(43,660		)	—			49			—			(43,611		)
	Net loss	$	(124,139	)	$	(35,022	)	$	(325	)	$	35,347		$	(124,139	)
	Total comprehensive loss	$	(126,769	)	$	(36,428	)	$	(325	)	$	36,753		$	(126,769	)
	Condensed Consolidating Statements of Operations
	Three Months Ended March 31, 2013
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	737,370		$	—		$	—		$	737,370
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	2,883			646,860			—			—			649,743
	Depreciation, depletion and amortization	1,406			108,778			9			—			110,193
	Amortization of acquired sales contracts, net	—			(2,810		)	—			—			(2,810		)
	Change in fair value of coal derivatives and coal trading activities, net	—			1,308			—			—			1,308
	Selling, general and administrative expenses	21,698			10,035			1,476			—			33,209
	Other operating income, net	(5,907		)	4,077			(1,012		)	—			(2,842		)
		20,080			768,248			473			—			788,801
	Income from investment in subsidiaries	(2,871		)	—			—			2,871			—
	Income (loss) from operations	(22,951		)	(30,878		)	(473		)	2,871			(51,431		)
	Interest expense, net
	Interest expense	(110,827		)	(6,442		)	(1,041		)	23,236			(95,074		)
	Interest and investment income	9,098			15,443			1,531			(23,236		)	2,836
		(101,729		)	9,001			490			—			(92,238		)
	Income (loss) from continuing operations before income taxes	(124,680		)	(21,877		)	17			2,871			(143,669		)
	Benefit from income taxes	(59,353		)	—			—			—			(59,353		)
	Income (loss) from continuing operations	(65,327		)	(21,877		)	17			2,871			(84,316		)
	Income from discontinued operations, net of tax	(4,722		)	18,989			—			—			14,267
	Net income (loss)	$	(70,049	)	$	(2,888	)	$	17		$	2,871		$	(70,049	)
	Total comprehensive income (loss)	$	(68,558	)	$	(3,324	)	$	17		$	3,307		$	(68,558	)
	Condensed Consolidating Balance Sheets
	March 31, 2014
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Assets
	Cash and cash equivalents	$	753,902		$	100,353		$	11,506		$	—		$	865,761
	Short term investments	248,572			—			—			—			248,572
	Receivables	33,115			16,594			229,737			(4,634		)	274,812
Inventories	—			224,806			—			—			224,806
Other	80,500			42,347			530			—			123,377
Total current assets	1,116,089			384,100			241,773			(4,634		)	1,737,328
Property, plant and equipment, net	23,765			6,592,317			28			34			6,616,144
Investment in subsidiaries	7,724,424			—			—			(7,724,424		)	—
Intercompany receivables	—			2,079,874			—			(2,079,874		)	—
Note receivable from Arch Western	675,000			—			—			(675,000		)	—
Other	157,663			311,976			73			—			469,712
Total other assets	8,557,087			2,391,850			73			(10,479,298		)	469,712
Total assets	$	9,696,941		$	9,368,267		$	241,874		$	(10,483,898	)	$	8,823,184
Liabilities and Stockholders’ Equity
Accounts payable	$	18,326		$	141,921		$	114		$	—		$	160,361
Accrued expenses and other current liabilities	105,706			226,757			732			(4,634		)	328,561
Current maturities of debt	25,481			4,469			—			—			29,950
Total current liabilities	149,513			373,147			846			(4,634		)	518,872
Long-term debt	5,095,777			17,218			—			—			5,112,995
Intercompany payables	1,865,706			—			214,168			(2,079,874		)	—
Note payable to Arch Coal	—			675,000			—			(675,000		)	—
Asset retirement obligations	1,018			389,390			—			—			390,408
Accrued pension benefits	2,873			7,611			—			—			10,484
Accrued postretirement benefits other than pension	4,213			33,782			—			—			37,995
Accrued workers’ compensation	27,606			48,211			—			—			75,817
Deferred income taxes	368,057			—			—			—			368,057
Other noncurrent liabilities	55,522			126,039			305			—			181,866
Total liabilities	7,570,285			1,670,398			215,319			(2,759,508		)	6,696,494
Stockholders’ equity	2,126,656			7,697,869			26,555			(7,724,390		)	2,126,690
Total liabilities and stockholders’ equity	$	9,696,941		$	9,368,267		$	241,874		$	(10,483,898	)	$	8,823,184
Condensed Consolidating Balance Sheets
December 31, 2013
	Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
				Subsidiaries			Subsidiaries
	(In thousands)
Assets
Cash and cash equivalents	$	799,333		$	100,418		$	11,348		$	—		$	911,099
Short term investments	248,414			—			—			—			248,414
Receivables	14,177			23,018			197,015			(4,637		)	229,573
Inventories	—			264,161			—			—			264,161
Other	84,401			43,617			806			—			128,824
Total current assets	1,146,325			431,214			209,169			(4,637		)	1,782,071
Property, plant and equipment, net	24,851			6,709,398			37			—			6,734,286
Investment in subsidiaries	7,741,589			—			—			(7,741,589		)	—
Intercompany receivables				1,953,719			(181,095		)	(1,772,624		)	—
Note receivable from Arch Western	675,000			—			—			(675,000		)	—
Other	162,287			311,463			86			—			473,836
Total other assets	8,578,876			2,265,182			(181,009		)	(10,189,213		)	473,836
Total assets	$	9,750,052		$	9,405,794		$	28,197		$	(10,193,850	)	$	8,990,193
Liabilities and Stockholders’ Equity
Accounts payable	$	17,781		$	158,224		$	137		$	—		$	176,142
Accrued expenses and other current liabilities	53,779			228,664			781			(4,637		)	278,587
Current maturities of debt	28,882			4,611			—			—			33,493
Total current liabilities	100,442			391,499			918			(4,637		)	488,222
Long-term debt	5,099,833			18,169			—						5,118,002
Intercompany payables	1,772,624			—			—			(1,772,624		)	—
Note payable to Arch Coal	—			675,000			—			(675,000		)	—
Asset retirement obligations	1,095			401,618			—			—			402,713
Accrued pension benefits	7,797			(686		)	—			—			7,111
Accrued postretirement benefits other than pension	12,079			27,176			—			—			39,255
Accrued workers’ compensation	21,546			56,516			—			—			78,062
Deferred income taxes	413,546			—			—			—			413,546
Other noncurrent liabilities	67,841			121,794			398			—			190,033
Total liabilities	7,496,803			1,691,086			1,316			(2,452,261		)	6,736,944
Stockholders’ equity	2,253,249			7,714,708			26,881			(7,741,589		)	2,253,249
Total liabilities and stockholders’ equity	$	9,750,052		$	9,405,794		$	28,197		$	(10,193,850	)	$	8,990,193
Condensed Consolidating Statements of Cash Flows
Three Months Ended March 31, 2014
	Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
				Subsidiaries			Subsidiaries
	(In thousands)
Cash provided by (used in) operating activities	$	(150,338	)	$	142,978		$	(32,915	)	$	—		$	(40,275	)
Investing Activities
Capital expenditures	(492		)	(13,962		)	—			—			(14,454		)
Additions to prepaid royalties	—			(591		)	—			—			(591		)
Proceeds from disposals and divestitures	26,319			1,876			—			—			28,195
Purchases of short term investments	(119,176		)	—			—			—			(119,176		)
Proceeds from sales of short term investments	117,681			—			—			—			117,681
Investments in and advances to affiliates	(1,016		)	(2,226		)	—			—			(3,242		)
Cash provided by (used in) investing activities	23,316			(14,903		)	—			—			8,413
Financing Activities
Payments on term loan	(4,875		)	—			—			—			(4,875		)
Net payments on other debt	(4,521		)	—			—			—			(4,521		)
Debt financing costs	(1,957		)	—			—			—			(1,957		)
Dividends paid	(2,123		)	—			—			—			(2,123		)
Transactions with affiliates, net	95,067			(128,140		)	33,073			—			—
Cash provided by (used in) financing activities	81,591			(128,140		)	33,073			—			(13,476		)
Increase (decrease) in cash and cash equivalents	(45,431		)	(65		)	158			—			(45,338		)
Cash and cash equivalents, beginning of period	799,333			100,418			11,348			—			911,099
Cash and cash equivalents, end of period	$	753,902		$	100,353		$	11,506		$	—		$	865,761
Condensed Consolidating Statements of Cash Flows
Three Months Ended March 31, 2013
	Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
				Subsidiaries			Subsidiaries
	(In thousands)
Cash provided by (used in) operating activities	$	(61,840	)	$	120,755		$	(15,624	)	$	—		$	43,291
Investing Activities
Capital expenditures	(615		)	(53,907		)	—			—			(54,522		)
Additions to prepaid royalties	—			(9,142		)	—			—			(9,142		)
Proceeds from disposals and divestitures	—			714			—			—			714
Purchases of short term investments	(26,787		)	—			—			—			(26,787		)
Proceeds from sales of short term investments	11,534			—			—			—			11,534
Investments in and advances to affiliates	(2,043		)	(2,383		)	—			128			(4,298		)
Change in restricted cash	1,163			—			—			—			1,163
Cash provided by (used in) investing activities	(16,748		)	(64,718		)	—			128			(81,338		)
Financing Activities
Contributions from parent	—			128			—			(128		)	—
Payments on term loan	(4,125		)	—			—			—			(4,125		)
Net payments on other debt	(5,836		)	(128		)	—			—			(5,964		)
Dividends paid	(6,367		)	—			—			—			(6,367		)
Transactions with affiliates, net	20,911			(36,076		)	15,165			—			—
Cash provided by (used in) financing activities	4,583			(36,076		)	15,165			(128		)	(16,456		)
Increase (decrease) in cash and cash equivalents	(74,005		)	19,961			(459		)	—			(54,503		)
Cash and cash equivalents, beginning of period	671,313			100,468			12,841			—			784,622
Cash and cash equivalents, end of period	$	597,308		$	120,429		$	12,382		$	—		$	730,119

Basis_of_Presentation_Policy

Basis of Presentation (Policy)	3 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis of Presentation	'
	The Company completed the sale of Canyon Fuel Company, LLC ("Canyon Fuel") on August 16, 2013. The results of Canyon Fuel have been segregated from continuing operations and are reflected, net of tax, as discontinued operations in the condensed consolidated statements of operations for the three months ended March 31, 2013.
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial reporting and U.S. Securities and Exchange Commission regulations. In the opinion of management, all adjustments, consisting of normal, recurring accruals considered necessary for a fair presentation, have been included. Results of operations for the three months ended March 31, 2014 are not necessarily indicative of results to be expected for the year ending December 31, 2014. These financial statements should be read in conjunction with the audited financial statements and related notes as of and for the year ended December 31, 2013 included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss)	'
	The following items are included in accumulated other comprehensive income:
						Pension,
						Postretirement
						and Other								Accumulated
						Post-								Other
		Derivative				Employment				Available-for-				Comprehensive
		Instruments				Benefits				Sale Securities				Loss
		(In thousands)
	Balance at December 31, 2013	$	565			$	31,112			$	6,015			$	37,692
	Unrealized gains (losses)	47				—				(1,657		)		(1,610		)
	Amounts reclassified from accumulated other comprehensive income	(194		)		(1,182		)		356				(1,020		)
	Balance at March 31, 2014	$	418			$	29,930			$	4,714			$	35,062
Schedule of comprehensive income reclassifications	'
	The following amounts were reclassified out of accumulated other comprehensive income:
			Amount Reclassified from
			Accumulated other comprehensive income										Line Item in the
	Details about accumulated other		Three months ended March 31,										Condensed Consolidated
	comprehensive income components		2014				2013						Statement of Operations
			(In thousands)
	Derivative instruments		$	303			$	859					Revenues
			(109		)		(309		)				Benefit from income taxes
			$	194			$	550					Net of tax
	Pension, postretirement and other post-employment benefits
	Amortization of prior service credits		$	2,626			$	2,908		1		1
	Amortization of actuarial gains (losses), net		(779		)		(4,862		)	1		1
			1,847				(1,954		)
			(665		)		703						Benefit from income taxes
			$	1,182			$	(1,251	)				Net of tax
	Available-for-sale securities		$	(556	)		$	(59	)	2		2	Interest and investment income
			200				21						Benefit from income taxes
			$	(356	)		$	(38	)				Net of tax
	1 Production-related benefits and workers' compensation costs are included in inventoriable production costs.
	2 The gains and losses on sales of available-for-sale-securities are determined on a specific identification basis.

Divestitures_Tables

Divestitures (Tables)	3 Months Ended
	Mar. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures	'
	The following table summarizes the assets and liabilities of the divested operations reflected in the December 31, 2013 consolidated balance sheet:
		(in thousands)
	Inventories	$	33,283
	Other current assets	1,032
	Net property, plant & equipment	104,587
	Other noncurrent assets	139
	Accounts payable and accrued expenses	13,005
	Other noncurrent liabilities	24,276
Results Of Discontinued Operations	'
	The following table summarizes the results of Canyon Fuel, reflected as discontinued operations in the condensed consolidated statement of operations through the date of disposition:
			Three Months Ended March 31, 2013
		(in thousands)
	Total revenues		$	88,132
	Income from discontinued operations before income taxes		$	18,989
	Less: income tax expense		4,722
	Income from discontinued operations		$	14,267
	Basic and diluted earnings per common share from discontinued operations		$	0.07

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories consist of the following:
		March 31,		31-Dec
		2014		2013
		(In thousands)
	Coal	$	98,125	$	117,531
	Repair parts and supplies	126,681		137,497
	Work-in-process	—		9,133
		$	224,806	$	264,161

Investments_in_AvailableforSal1

Investments in Available-for-Sale Securities (Tables)	3 Months Ended
	Mar. 31, 2014
Available-for-sale Securities [Abstract]	'
Available-for-sale Securities	'
	The Company's investments in available-for-sale marketable securities are as follows:
		March 31, 2014
											Balance Sheet
				Gross		Gross					Classification
				Unrealized		Unrealized			Fair		Short-Term		Other
		Cost Basis		Gains		Losses			Value		Investments		Assets
		(In thousands)
	Available-for-sale:
	Corporate notes and bonds	$	250,723	$	4	$	(2,155	)	$	248,572	$	248,572	$	—
	Equity securities	5,420		12,203		(2,698		)	14,925		—		14,925
	Total Investments	$	256,143	$	12,207	$	(4,853	)	$	263,497	$	248,572	$	14,925
		December 31, 2013
											Balance Sheet
				Gross		Gross					Classification
				Unrealized		Unrealized			Fair		Short-Term		Other
		Cost Basis		Gains		Losses			Value		Investments		Assets
		(In thousands)
	Available-for-sale:
	U.S. government and agency securities	$	65,002	$	11	$	(75	)	$	64,938	$	64,938	$	—
	Corporate notes and bonds	184,773		7		(1,304		)	183,476		183,476		—
	Equity securities	5,271		13,660		(2,902		)	16,029		—		16,029
	Total Investments	$	255,046	$	13,678	$	(4,281	)	$	264,443	$	248,414	$	16,029

Derivatives_Tables

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Price Risk Derivatives	'
	At March 31, 2014, the Company held derivatives for risk management purposes that are expected to settle in the following years:
	(Tons in thousands)		2014			2015			Total
	Coal sales		3,991			1,380			5,371
	Coal purchases		1,778			—			1,778
Disclosure Of Fair Value Of Derivatives	'
	The fair value and location of derivatives reflected in the accompanying condensed consolidated balance sheets are as follows:
			31-Mar-14											31-Dec-13
	Fair Value of Derivatives		Asset				Liability							Asset			Liability
	(In thousands)		Derivative				Derivative							Derivative			Derivative
	Derivatives Designated as Hedging Instruments
	Coal		$	1,101			$	(215	)					$	909		$	(26	)
	Derivatives Not Designated as Hedging Instruments
	Heating oil -- diesel purchases		2,683				—							4,681			—
	Heating oil -- fuel surcharges		152				—							422			—
	Coal -- held for trading purposes		75,886				(67,944		)					55,327			(45,763		)
	Coal -- risk management		4,543				(1,453		)					6,342			(1,950		)
	Natural gas		398				—							—			—
	Total		83,662				(69,397		)					66,772			(47,713		)
	Total derivatives		84,763				(69,612		)					67,681			(47,739		)
	Effect of counterparty netting		(69,612		)		69,612							(47,727		)	47,727
	Net derivatives as classified in the balance sheets		$	15,151			$	—			$	15,151		$	19,954		$	(12	)	$	19,942
					31-Mar-14				31-Dec-13
	Net derivatives as reflected on the balance sheets				2835
	Heating oil		Other current assets		$	2,835			$	5,103
	Coal		Coal derivative assets		12,316				14,851
			Accrued expenses and other current liabilities		—				(12		)
					$	15,151			$	19,942
Effects Of Derivatives On Measures Of Financial Performance	'
	The effects of derivatives on measures of financial performance are as follows:
	Derivatives used in Cash Flow Hedging Relationships (in thousands)
	For the Three Months Ended March 31,
			Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)								Gains (Losses) Reclassified from Other Comprehensive Income into Income
											(Effective Portion)
			2014				2013				2014			2013
	Coal sales	(1)	$	(515	)		$	(176	)		$	706		$	1,221
	Coal purchases	(2)	589				(182		)		(404		)	(362		)
	Totals		$	74			$	(358	)		$	302		$	859
	No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the three month periods ended March 31, 2014 and 2013.
	Derivatives Not Designated as Hedging Instruments (in thousands)
	For the Three Months Ended March 31,
			Gain (Loss) Recognized
			2014				2013
	Coal — unrealized	(3)	$	(1,302	)		$	1,470
	Coal — realized	(4)	$	2,879			$	9,217
	Natural gas  — unrealized	(3)	$	8			$	—
	Heating oil — diesel purchases	(4)	$	(2,963	)		$	(4,261	)
	Heating oil — fuel surcharges	(4)	$	(254	)		$	(565	)
	____________________________________________________________
	Location in statement of operations:
	(1) — Revenues
	(2) — Cost of sales
	(3) — Change in fair value of coal derivatives and coal trading activities, net
	(4) — Other operating income, net

Accrued_Expenses_and_Other_Cur1

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2014
Accrued Expenses and Other Current Liabilities [Abstract]	'
Schedule of Accrued Liabilities	'
	Accrued expenses and other current liabilities consist of the following:
		March 31,		December 31,
		2014		2013
		(In thousands)
	Payroll and employee benefits	$	58,220	$	67,621
	Taxes other than income taxes	112,406		114,664
	Interest	79,731		18,528
	Acquired sales contracts	14,439		14,373
	Workers’ compensation	16,470		12,434
	Asset retirement obligations	22,682		24,940
	Other	24,613		26,027
		$	328,561	$	278,587

Debt_and_Financing_Arrangement1

Debt and Financing Arrangements (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Debt	'
		March 31,		December 31,
		2014		2013
		(In thousands)
	Term loan due 2018 ($1.92 billion and $1.93 billion face value, respectively)	$	1,902,731	$	1,906,975
	7.00% senior notes due 2019 at par	1,000,000		1,000,000
	9.875% senior notes due 2019 ($375.0 million face value)	362,573		362,358
	8.00% senior secured notes due 2019 at par	350,000		350,000
	7.25% senior notes due 2020 at par	500,000		500,000
	7.25% senior notes due 2021 at par	1,000,000		1,000,000
	Other	27,641		32,162
		5,142,945		5,151,495
	Less current maturities of debt	29,950		33,493
	Long-term debt	$	5,112,995	$	5,118,002

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Summary Of Financial Assets And Liabilities Accounted For At Fair Value	'
	The table below sets forth, by level, the Company’s financial assets and liabilities that are recorded at fair value in the accompanying condensed consolidated balance sheet:
		31-Mar-14
		Total			Level 1		Level 2		Level 3
		(In thousands)
	Assets:
	Investments in marketable securities	$	263,497		$	14,925	$	248,572	$	—
	Derivatives	15,151			10,956		218		3,977
	Total assets	$	278,648		$	25,881	$	248,790	$	3,977
Summary Of Change In The Fair Values Of Financial Instruments Categorized As Level 3	'
	The following table summarizes the change in the fair values of financial instruments categorized as level 3.
		Three Months Ended March 31, 2014
		(In thousands)
	Balance, beginning of period	$	4,946
	Realized and unrealized losses recognized in earnings, net	(2,925		)
	Purchases	1,956
	Ending balance	$	3,977

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2014
Pension and Other Postretirement Benefit Expense [Abstract]	'
Pension Benefit Costs	'
	The following table details the components of pension benefit costs (credits):
		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Service cost	$	5,924		$	7,700
	Interest cost	4,364			3,926
	Expected return on plan assets	(5,978		)	(5,806		)
	Amortization of prior service costs (credits)	(54		)	(158		)
	Amortization of other actuarial losses	948			4,551
	Net benefit cost	$	5,204		$	10,213
Other Postretirement Benefit Costs	'
	The following table details the components of other postretirement benefit costs (credits):
		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Service cost	$	444		$	556
	Interest cost	464			431
	Amortization of prior service credits	(2,501		)	(2,750		)
	Amortization of other actuarial losses (gains)	(170		)	77
	Net benefit credit	$	(1,763	)	$	(1,686	)

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Schedule Of Operating Segment Results	'
		PRB			APP			Other		Corporate,			Consolidated
								Operating		Other and
								Segments		Eliminations
		(in thousands)
	Three Months Ended March 31, 2014
	Revenues	$	358,607		$	279,137		$	98,227	$	—		$	735,971
	Income (loss) from operations	(4,898		)	(25,728		)	1,635		(44,131		)	(73,122		)
	Depreciation, depletion and amortization	39,245			54,988			9,519		671			104,423
	Amortization of acquired sales contracts, net	(789		)	(2,974		)	67		—			(3,696		)
	Capital expenditures	2,094			8,156			1,801		2,403			14,454
	Three Months Ended March 31, 2013
	Revenues	$	361,946		$	282,618		$	92,806	$	—		$	737,370
	Income (loss) from operations	15,516			(27,116		)	7,384		(47,215		)	(51,431		)
	Depreciation, depletion and amortization	42,227			55,331			11,304		1,331			110,193
	Amortization of acquired sales contracts, net	(1,199		)	(2,472		)	861		—			(2,810		)
	Capital expenditures	2,157			49,297			763		2,305			54,522
Reconciliation Statement Of Segment Income From Operations To Consolidated Income Before Income Taxes	'
	A reconciliation of segment income (loss) from operations to consolidated loss before income taxes follows:
		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Loss from operations	$	(73,122	)	$	(51,431	)
	Interest expense	(96,471		)	(95,074		)
	Interest and investment income	1,843			2,836
	Loss from continuing operations before income taxes	$	(167,750	)	$	(143,669	)

Supplemental_Condensed_Consoli1

Supplemental Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Mar. 31, 2014
Supplemental Condensed Consolidating Financial Information [Abstract]	'
Schedule of Condensed Consolidating Statements of Income	'
	Condensed Consolidating Statements of Operations
	Three Months Ended March 31, 2014
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	735,971		$	—		$	—		$	735,971
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	3,389			683,775			—			(850		)	686,314
	Depreciation, depletion and amortization	1,472			102,942			9			—			104,423
	Amortization of acquired sales contracts, net	—			(3,696		)	—			—			(3,696		)
	Change in fair value of coal derivatives and coal trading activities, net	—			914			—			—			914
	Selling, general and administrative expenses	19,944			7,865			1,803			(476		)	29,136
	Other operating income, net	1,593			(9,480		)	(1,437		)	1,326			(7,998		)
		26,398			782,320			375			—			809,093
	Loss from investment in subsidiaries	(35,347		)	—			—			35,347			—
	Loss from operations	(61,745		)	(46,349		)	(375		)	35,347			(73,122		)
	Interest expense, net
	Interest expense	(113,655		)	(6,324		)	(1,050		)	24,558			(96,471		)
	Interest and investment income	7,601			17,651			1,149			(24,558		)	1,843
		(106,054		)	11,327			99			—			(94,628		)
	Loss from continuing operations before income taxes	(167,799		)	(35,022		)	(276		)	35,347			(167,750		)
	Provision for (benefit from) income taxes	(43,660		)	—			49			—			(43,611		)
	Net loss	$	(124,139	)	$	(35,022	)	$	(325	)	$	35,347		$	(124,139	)
	Total comprehensive loss	$	(126,769	)	$	(36,428	)	$	(325	)	$	36,753		$	(126,769	)
	Condensed Consolidating Statements of Operations
	Three Months Ended March 31, 2013
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	737,370		$	—		$	—		$	737,370
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	2,883			646,860			—			—			649,743
	Depreciation, depletion and amortization	1,406			108,778			9			—			110,193
	Amortization of acquired sales contracts, net	—			(2,810		)	—			—			(2,810		)
	Change in fair value of coal derivatives and coal trading activities, net	—			1,308			—			—			1,308
	Selling, general and administrative expenses	21,698			10,035			1,476			—			33,209
	Other operating income, net	(5,907		)	4,077			(1,012		)	—			(2,842		)
		20,080			768,248			473			—			788,801
	Income from investment in subsidiaries	(2,871		)	—			—			2,871			—
	Income (loss) from operations	(22,951		)	(30,878		)	(473		)	2,871			(51,431		)
	Interest expense, net
	Interest expense	(110,827		)	(6,442		)	(1,041		)	23,236			(95,074		)
	Interest and investment income	9,098			15,443			1,531			(23,236		)	2,836
		(101,729		)	9,001			490			—			(92,238		)
	Income (loss) from continuing operations before income taxes	(124,680		)	(21,877		)	17			2,871			(143,669		)
	Benefit from income taxes	(59,353		)	—			—			—			(59,353		)
	Income (loss) from continuing operations	(65,327		)	(21,877		)	17			2,871			(84,316		)
	Income from discontinued operations, net of tax	(4,722		)	18,989			—			—			14,267
	Net income (loss)	$	(70,049	)	$	(2,888	)	$	17		$	2,871		$	(70,049	)
	Total comprehensive income (loss)	$	(68,558	)	$	(3,324	)	$	17		$	3,307		$	(68,558	)
Schedule of Condensed Consolidating Balance Sheets	'
	Condensed Consolidating Balance Sheets
	March 31, 2014
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Assets
	Cash and cash equivalents	$	753,902		$	100,353		$	11,506		$	—		$	865,761
	Short term investments	248,572			—			—			—			248,572
	Receivables	33,115			16,594			229,737			(4,634		)	274,812
	Inventories	—			224,806			—			—			224,806
	Other	80,500			42,347			530			—			123,377
	Total current assets	1,116,089			384,100			241,773			(4,634		)	1,737,328
	Property, plant and equipment, net	23,765			6,592,317			28			34			6,616,144
	Investment in subsidiaries	7,724,424			—			—			(7,724,424		)	—
	Intercompany receivables	—			2,079,874			—			(2,079,874		)	—
	Note receivable from Arch Western	675,000			—			—			(675,000		)	—
	Other	157,663			311,976			73			—			469,712
	Total other assets	8,557,087			2,391,850			73			(10,479,298		)	469,712
	Total assets	$	9,696,941		$	9,368,267		$	241,874		$	(10,483,898	)	$	8,823,184
	Liabilities and Stockholders’ Equity
	Accounts payable	$	18,326		$	141,921		$	114		$	—		$	160,361
	Accrued expenses and other current liabilities	105,706			226,757			732			(4,634		)	328,561
	Current maturities of debt	25,481			4,469			—			—			29,950
	Total current liabilities	149,513			373,147			846			(4,634		)	518,872
	Long-term debt	5,095,777			17,218			—			—			5,112,995
	Intercompany payables	1,865,706			—			214,168			(2,079,874		)	—
	Note payable to Arch Coal	—			675,000			—			(675,000		)	—
	Asset retirement obligations	1,018			389,390			—			—			390,408
	Accrued pension benefits	2,873			7,611			—			—			10,484
	Accrued postretirement benefits other than pension	4,213			33,782			—			—			37,995
	Accrued workers’ compensation	27,606			48,211			—			—			75,817
	Deferred income taxes	368,057			—			—			—			368,057
	Other noncurrent liabilities	55,522			126,039			305			—			181,866
	Total liabilities	7,570,285			1,670,398			215,319			(2,759,508		)	6,696,494
	Stockholders’ equity	2,126,656			7,697,869			26,555			(7,724,390		)	2,126,690
	Total liabilities and stockholders’ equity	$	9,696,941		$	9,368,267		$	241,874		$	(10,483,898	)	$	8,823,184
	Condensed Consolidating Balance Sheets
	December 31, 2013
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Assets
	Cash and cash equivalents	$	799,333		$	100,418		$	11,348		$	—		$	911,099
	Short term investments	248,414			—			—			—			248,414
	Receivables	14,177			23,018			197,015			(4,637		)	229,573
	Inventories	—			264,161			—			—			264,161
	Other	84,401			43,617			806			—			128,824
	Total current assets	1,146,325			431,214			209,169			(4,637		)	1,782,071
	Property, plant and equipment, net	24,851			6,709,398			37			—			6,734,286
	Investment in subsidiaries	7,741,589			—			—			(7,741,589		)	—
	Intercompany receivables				1,953,719			(181,095		)	(1,772,624		)	—
	Note receivable from Arch Western	675,000			—			—			(675,000		)	—
	Other	162,287			311,463			86			—			473,836
	Total other assets	8,578,876			2,265,182			(181,009		)	(10,189,213		)	473,836
	Total assets	$	9,750,052		$	9,405,794		$	28,197		$	(10,193,850	)	$	8,990,193
	Liabilities and Stockholders’ Equity
	Accounts payable	$	17,781		$	158,224		$	137		$	—		$	176,142
	Accrued expenses and other current liabilities	53,779			228,664			781			(4,637		)	278,587
	Current maturities of debt	28,882			4,611			—			—			33,493
	Total current liabilities	100,442			391,499			918			(4,637		)	488,222
	Long-term debt	5,099,833			18,169			—						5,118,002
	Intercompany payables	1,772,624			—			—			(1,772,624		)	—
	Note payable to Arch Coal	—			675,000			—			(675,000		)	—
Asset retirement obligations	1,095			401,618			—			—			402,713
Accrued pension benefits	7,797			(686		)	—			—			7,111
Accrued postretirement benefits other than pension	12,079			27,176			—			—			39,255
Accrued workers’ compensation	21,546			56,516			—			—			78,062
Deferred income taxes	413,546			—			—			—			413,546
Other noncurrent liabilities	67,841			121,794			398			—			190,033
Total liabilities	7,496,803			1,691,086			1,316			(2,452,261		)	6,736,944
Stockholders’ equity	2,253,249			7,714,708			26,881			(7,741,589		)	2,253,249
Total liabilities and stockholders’ equity	$	9,750,052		$	9,405,794		$	28,197		$	(10,193,850	)	$	8,990,193
Schedule of Condensed Consolidating Statements of Cash Flows	'
	Condensed Consolidating Statements of Cash Flows
	Three Months Ended March 31, 2014
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Cash provided by (used in) operating activities	$	(150,338	)	$	142,978		$	(32,915	)	$	—		$	(40,275	)
	Investing Activities
	Capital expenditures	(492		)	(13,962		)	—			—			(14,454		)
	Additions to prepaid royalties	—			(591		)	—			—			(591		)
	Proceeds from disposals and divestitures	26,319			1,876			—			—			28,195
	Purchases of short term investments	(119,176		)	—			—			—			(119,176		)
	Proceeds from sales of short term investments	117,681			—			—			—			117,681
	Investments in and advances to affiliates	(1,016		)	(2,226		)	—			—			(3,242		)
	Cash provided by (used in) investing activities	23,316			(14,903		)	—			—			8,413
	Financing Activities
	Payments on term loan	(4,875		)	—			—			—			(4,875		)
	Net payments on other debt	(4,521		)	—			—			—			(4,521		)
	Debt financing costs	(1,957		)	—			—			—			(1,957		)
	Dividends paid	(2,123		)	—			—			—			(2,123		)
	Transactions with affiliates, net	95,067			(128,140		)	33,073			—			—
	Cash provided by (used in) financing activities	81,591			(128,140		)	33,073			—			(13,476		)
	Increase (decrease) in cash and cash equivalents	(45,431		)	(65		)	158			—			(45,338		)
	Cash and cash equivalents, beginning of period	799,333			100,418			11,348			—			911,099
	Cash and cash equivalents, end of period	$	753,902		$	100,353		$	11,506		$	—		$	865,761
	Condensed Consolidating Statements of Cash Flows
	Three Months Ended March 31, 2013
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Cash provided by (used in) operating activities	$	(61,840	)	$	120,755		$	(15,624	)	$	—		$	43,291
	Investing Activities
	Capital expenditures	(615		)	(53,907		)	—			—			(54,522		)
	Additions to prepaid royalties	—			(9,142		)	—			—			(9,142		)
	Proceeds from disposals and divestitures	—			714			—			—			714
	Purchases of short term investments	(26,787		)	—			—			—			(26,787		)
	Proceeds from sales of short term investments	11,534			—			—			—			11,534
	Investments in and advances to affiliates	(2,043		)	(2,383		)	—			128			(4,298		)
	Change in restricted cash	1,163			—			—			—			1,163
	Cash provided by (used in) investing activities	(16,748		)	(64,718		)	—			128			(81,338		)
	Financing Activities
	Contributions from parent	—			128			—			(128		)	—
	Payments on term loan	(4,125		)	—			—			—			(4,125		)
	Net payments on other debt	(5,836		)	(128		)	—			—			(5,964		)
	Dividends paid	(6,367		)	—			—			—			(6,367		)
	Transactions with affiliates, net	20,911			(36,076		)	15,165			—			—
	Cash provided by (used in) financing activities	4,583			(36,076		)	15,165			(128		)	(16,456		)
	Increase (decrease) in cash and cash equivalents	(74,005		)	19,961			(459		)	—			(54,503		)
	Cash and cash equivalents, beginning of period	671,313			100,468			12,841			—			784,622
	Cash and cash equivalents, end of period	$	597,308		$	120,429		$	12,382		$	—		$	730,119

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2013	$37,692
Unrealized gains (losses)	-1,610
Amounts reclassified from accumulated other comprehensive income	-1,020
Balance at March 31, 2014	35,062
Derivative Instruments [Member]	'
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2013	565
Unrealized gains (losses)	47
Amounts reclassified from accumulated other comprehensive income	-194
Balance at March 31, 2014	418
Pension, Postretirement and Other Postemployment Benefits [Member]	'
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2013	31,112
Unrealized gains (losses)	0
Amounts reclassified from accumulated other comprehensive income	-1,182
Balance at March 31, 2014	29,930
Available-for-Sale Securities [Member]	'
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2013	6,015
Unrealized gains (losses)	-1,657
Amounts reclassified from accumulated other comprehensive income	356
Balance at March 31, 2014	$4,714

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income (Schedule of Reclassifications) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Revenues	$735,971	$737,370
Benefit from income taxes	43,611	59,353
Net loss	-124,139	-70,049
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivative Instruments [Member]	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Revenues	303	859
Benefit from income taxes	-109	-309
Net loss	194	550
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension, Postretirement and Other Postemployment Benefits [Member]	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Amortization of prior service credits	2,626	2,908
Amortization of actuarial gains (losses), net	-779	-4,862
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	1,847	-1,954
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	-665	703
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	1,182	-1,251
Reclassification out of Accumulated Other Comprehensive Income [Member] | Available-for-Sale Securities [Member]	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'
Interest and investment income	-556	-59
Benefit from income taxes	200	21
Net loss	($356)	($38)

Divestitures_Narrative_Details

Divestitures (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]	'
Total Consideration for Disposal Group	$45.50
Proceeds from divestiture of businesses	26.3
Net gain on divestitures	13.8
Notes Receivable [Member]	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'
Noncash or Part Noncash Divestiture, Amount of Consideration Received	19
June 30, 2014 [Member] | Notes Receivable [Member]	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'
Noncash or Part Noncash Divestiture, Amount of Consideration Received	8
December 31, 2014 [Member] | Notes Receivable [Member]	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'
Noncash or Part Noncash Divestiture, Amount of Consideration Received	$11

Divestitures_Asset_and_Liabili

Divestitures (Asset and Liabilities of Divested Operations) (Details) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Discontinued Operations and Disposal Groups [Abstract]	'
Disposal Group, Including Discontinued Operation, Inventory	$33,283
Assets of Disposal Group, Including Discontinued Operation, Current	1,032
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net	104,587
Assets of Disposal Group, Including Discontinued Operation, Noncurrent	139
Liabilities of Disposal Group, Including Discontinued Operation, Current	13,005
Liabilities of Disposal Group, Including Discontinued Operation, Noncurrent	$24,276

Divestitures_Results_of_Discon

Divestitures (Results of Discontinued Operations) (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
Total revenues	$88,132
Income from discontinued operations before income taxes	18,989
Less: income tax expense	4,722
Income from discontinued operations	$14,267
Basic and diluted earnings per common share from discontinued operations	$0.07

Inventories_Details

Inventories (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]	'	'
Coal	$98,125,000	$117,531,000
Repair parts and supplies	126,681,000	137,497,000
Work-in-process	0	9,133,000
Inventories	224,806,000	264,161,000
Allowance for slow-moving and obsolete inventories	$8,600,000	$8,400,000

Investments_in_AvailableforSal2

Investments in Available-for-Sale Securities (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	$256,143	$255,046
Gross Unrealized Gains	12,207	13,678
Gross Unrealized Losses	-4,853	-4,281
Fair Value	263,497	264,443
Short term investments	248,572	248,414
US Government Agencies Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	'	65,002
Available-for-sale Debt Securities Gross Unrealized Gain	'	11
Available-for-sale Debt Securities, Gross Unrealized Loss	'	-75
Fair Value	'	64,938
Corporate Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	250,723	184,773
Available-for-sale Debt Securities Gross Unrealized Gain	4	7
Available-for-sale Debt Securities, Gross Unrealized Loss	-2,155	-1,304
Fair Value	248,572	183,476
Equity Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	5,420	5,271
Available-for-sale Equity Securities, Gross Unrealized Gain	12,203	13,660
Available-for-sale Equity Securities, Gross Unrealized Loss	-2,698	-2,902
Fair Value	14,925	16,029
Short-term Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
U.S. government and agency securities	'	64,938
Corporate notes and bonds	248,572	183,476
Equity securities	0	0
Short term investments	248,572	248,414
Other Assets [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
U.S. government and agency securities	'	0
Corporate notes and bonds	0	0
Equity securities	$14,925	$16,029

Investments_in_AvailableforSal3

Investments in Available-for-Sale Securities (Narrative) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Available-for-sale Securities [Abstract]	'	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$200.40	$164.30
Available-for-sale Securities, Continuous Unrealized Loss Position, Greater than Twelve Months, Fair Value	$34.70	$48.70

Derivatives_Narrative_Details

Derivatives (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Derivative [Line Items]	'	'	'
Current asset (liability) for the right to reclaim cash collateral	$6.50	'	$2.20
Net unrealized and realized gains (losses) related to trading portfolio	0.4	-2.8	'
Gain on derivative contracts designated as hedge instruments in cash flow hedges to be reclassified from OCI into earnings during the next twelve months	0.9	'	'
Year One [Member]	'	'	'
Derivative [Line Items]	'	'	'
Value of trading portfolio realized	6.6	'	'
Year Two [Member]	'	'	'
Derivative [Line Items]	'	'	'
Value of trading portfolio realized	$1.40	'	'
Diesel Purchases [Member] | Year One [Member]	'	'	'
Derivative [Line Items]	'	'	'
Percent of expected requirements covered	87.00%	'	'
Diesel Purchases [Member] | Year Two [Member]	'	'	'
Derivative [Line Items]	'	'	'
Percent of expected requirements covered	30.00%	'	'
Diesel Purchases [Member] | Heating Oil [Member]	'	'	'
Derivative [Line Items]	'	'	'
Quantities under derivative contracts	61,000,000	'	'
Diesel Purchases [Member] | Minimum Annual Purchase [Member]	'	'	'
Derivative [Line Items]	'	'	'
Gallons of diesel fuel purchased annually	57,000,000	'	'
Diesel Purchases [Member] | Maximum [Member]	'	'	'
Derivative [Line Items]	'	'	'
Gallons of diesel fuel purchased annually	67,000,000	'	'
Diesel Usage Fuel Surcharges [Member] | Heating Oil [Member] | Year One [Member]	'	'	'
Derivative [Line Items]	'	'	'
Quantities under derivative contracts	3,800,000	'	'

Derivatives_Schedule_of_Price_

Derivatives (Schedule of Price Risk Derivatives) (Details)	Mar. 31, 2014
	T
Coal sales [Member]	'
Derivative [Line Items]	'
Derivatives Held	5,371,000
Coal purchases [Member]	'
Derivative [Line Items]	'
Derivatives Held	1,778,000
Year One [Member] | Coal sales [Member]	'
Derivative [Line Items]	'
Derivatives Held	3,991,000
Year One [Member] | Coal purchases [Member]	'
Derivative [Line Items]	'
Derivatives Held	1,778,000
Year Two [Member] | Coal sales [Member]	'
Derivative [Line Items]	'
Derivatives Held	1,380,000
Year Two [Member] | Coal purchases [Member]	'
Derivative [Line Items]	'
Derivatives Held	0

Derivatives_Disclosure_Of_Fair

Derivatives (Disclosure Of Fair Value Of Derivatives) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative [Line Items]	'	'
Derivative Asset	$15,151	$19,954
Derivative Liability	0	-12
Derivative Assets	84,763	67,681
Derivative Liabilities	-69,612	-47,739
Net derivatives as classified in the balance sheet	15,151	19,942
Not Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	83,662	66,772
Derivative Liabilities	-69,397	-47,713
Not Designated as Hedging Instrument [Member] | Coal Contract [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	75,886	55,327
Derivative Liabilities	-67,944	-45,763
Netting [Member]	'	'
Derivative [Line Items]	'	'
Derivative Asset	-69,612	-47,727
Derivative Liability	69,612	47,727
Heating Oil-Diesel Purchases [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Price Risk Derivative Instruments Not Designated as Hedging Instruments Asset, at Fair Value	2,683	4,681
Price Risk Derivative Instruments Not Designated as Hedging Instruments Liability, at Fair Value	'	'
Heating Oil-Fuel Surcharges [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Price Risk Derivative Instruments Not Designated as Hedging Instruments Asset, at Fair Value	152	422
Price Risk Derivative Instruments Not Designated as Hedging Instruments Liability, at Fair Value	'	'
Coal Contract [Member] | Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	1,101	909
Derivative Liabilities	-215	-26
Coal Contract [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Price Risk Derivative Instruments Not Designated as Hedging Instruments Asset, at Fair Value	4,543	6,342
Price Risk Derivative Instruments Not Designated as Hedging Instruments Liability, at Fair Value	-1,453	-1,950
Natural Gas [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Price Risk Derivative Instruments Not Designated as Hedging Instruments Asset, at Fair Value	398	0
Price Risk Derivative Instruments Not Designated as Hedging Instruments Liability, at Fair Value	$0	$0

Derivatives_Net_Derivatives_As

Derivatives (Net Derivatives As Reflected On The Balance Sheets) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	$15,151	$19,942
Heating Oil [Member] | Other Current Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	2,835	5,103
Coal Contract [Member] | Coal Derivative Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	12,316	14,851
Coal Contract [Member] | Accrued expenses and other current liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	$0	($12)

Derivatives_Effects_Of_Derivat

Derivatives (Effects Of Derivatives On Measures Of Financial Performance) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss) Recognized in OCI (Effective Portion)	$74	($358)
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	302	859
Not Designated as Hedging Instrument [Member] | Coal Contract [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Unrealized Gain (Loss) on Derivatives	-1,302	1,470
Coal derivative settlements, non-hedging	2,879	9,217
Not Designated as Hedging Instrument [Member] | Heating Oil-Fuel Surcharges [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Realized Gains (Losses)	-254	-565
Not Designated as Hedging Instrument [Member] | Heating Oil-Diesel Purchases [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Realized Gains (Losses)	-2,963	-4,261
Not Designated as Hedging Instrument [Member] | Natural Gas [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Unrealized Gain (Loss) on Derivatives	8	0
Coal sales [Member] | Coal Contract [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss) Recognized in OCI (Effective Portion)	-515	-176
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	706	1,221
Coal purchases [Member] | Coal Contract [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss) Recognized in OCI (Effective Portion)	589	-182
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	($404)	($362)

Accrued_Expenses_and_Other_Cur2

Accrued Expenses and Other Current Liabilities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Expenses and Other Current Liabilities [Abstract]	'	'
Payroll and employee benefits	$58,220	$67,621
Taxes other than income taxes	112,406	114,664
Interest	79,731	18,528
Acquired sales contracts	14,439	14,373
Workers’ compensation	16,470	12,434
Asset retirement obligations	22,682	24,940
Other	24,613	26,027
Accrued Liabilities, Current	$328,561	$278,587

Debt_and_Financing_Arrangement2

Debt and Financing Arrangements (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Other	$27,641,000	$32,162,000
Total	5,142,945,000	5,151,495,000
Current maturities of debt	29,950,000	33,493,000
Long-term debt	5,112,995,000	5,118,002,000
Available borrowing capacity under lines of credit	250,100,000	'
Loans Payable [Member]	'	'
Debt Instrument [Line Items]	'	'
Term loan due 2018 ($1.92 billion and $1.93 billion face value, respectively)	1,902,731,000	1,906,975,000
Debt Instrument, Basis Spread on Variable Rate	4.50%	'
Debt Instrument, Face Amount	1,920,000,000	1,930,000,000
7.00% Senior Notes Due 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior notes	1,000,000,000	1,000,000,000
Senior notes interest rate	7.00%	'
9.875% Senior Notes Due 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior notes	362,573,000	362,358,000
Senior notes interest rate	9.88%	'
Debt Instrument, Face Amount	375,000,000	'
8.00% Senior Secured Notes due 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior notes	350,000,000	350,000,000
Senior notes interest rate	8.00%	'
7.25% Senior Notes Due 2020 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior notes	500,000,000	500,000,000
Senior notes interest rate	7.25%	'
7.25% Senior Notes Due 2021 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior notes	$1,000,000,000	$1,000,000,000
Senior notes interest rate	7.25%	'

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (Valuation Allowance, Operating Loss Carryforwards [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Internal Revenue Service (IRS) [Member]	'
Valuation Allowance [Line Items]	'
Valuation Allowance, Deferred Tax Asset, Change in Amount	$21.60
State and Local Jurisdiction [Member]	'
Valuation Allowance [Line Items]	'
Valuation Allowance, Deferred Tax Asset, Change in Amount	$2.20

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014
			Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Net unrealized losses related to level 3 financial instruments	'	'	$2,600,000
Fair value of senior notes and other long-term debt, including amounts classified as current	$4,500,000,000	$4,600,000,000	'

Fair_Value_Measurements_Summar

Fair Value Measurements (Summary Of Change In The Fair Values Of Financial Instruments Categorized As Level 3) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'
Balance, beginning of period	$4,946
Realized and unrealized losses recognized in earnings, net	-2,925
Purchases	1,956
Ending balance	$3,977

Fair_Value_Measurements_Summar1

Fair Value Measurements (Summary Of Financial Assets And Liabilities Accounted For At Fair Value) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:	'	'
Investments in marketable securities	$263,497	$264,443
Derivatives	15,151	19,954
Total assets	278,648	'
Level 1 [Member]	'	'
Assets:	'	'
Investments in marketable securities	14,925	'
Derivatives	10,956	'
Total assets	25,881	'
Level 2 [Member]	'	'
Assets:	'	'
Investments in marketable securities	248,572	'
Derivatives	218	'
Total assets	248,790	'
Level 3 [Member]	'	'
Assets:	'	'
Investments in marketable securities	'	'
Derivatives	3,977	'
Total assets	$3,977	'

Loss_Per_Common_Share_Narrativ

Loss Per Common Share (Narrative) (Details)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Effect of options to purchase common stock	6.9	8.6

Employee_Benefit_Plans_Pension

Employee Benefit Plans (Pension And Other Postretirement Benefit Costs) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Pension Plans, Defined Benefit [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	$5,924	$7,700
Interest cost	4,364	3,926
Expected return on plan assets	-5,978	-5,806
Amortization of prior service cost (credit)	-54	-158
Amortization of other actuarial (gains) losses	948	4,551
Net benefit cost	5,204	10,213
Other Postretirement Benefit Plans, Defined Benefit [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	444	556
Interest cost	464	431
Amortization of prior service cost (credit)	-2,501	-2,750
Amortization of other actuarial (gains) losses	-170	77
Net benefit cost	($1,763)	($1,686)

Commitments_and_Contingencies_

Commitments and Contingencies (Narrative) (Details) (USD $)	1 Months Ended						1 Months Ended
	Jul. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Aug. 25, 2011	2-May-11	Aug. 13, 2007	Feb. 01, 2011	Feb. 01, 2011	Aug. 25, 2011	Aug. 25, 2011
							Maximum [Member]	Minimum [Member]	past damages [Member]	future damages [Member]
Purchase replacement coal, excess of	'	'	'	'	'	$100,000,000	'	'	'	'
Aggregate amount of past and future damages	'	'	'	'	'	'	377,000,000	228,000,000	'	'
Damages and interest awarded	'	'	'	104,100,000	104,100,000	'	'	'	13,800,000	90,300,000
Payments for Legal Settlements	15,600,000	'	'	'	'	'	'	'	'	'
Amount accrued	'	23,100,000	30,400,000	'	'	'	'	'	'	'
Amount accrued current portion	'	$10,100,000	$11,700,000	'	'	'	'	'	'	'

Segment_Information_Schedule_O

Segment Information (Schedule Of Operating Segment Results) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]	'	'
Revenues	$735,971	$737,370
Income (loss) from operations	-73,122	-51,431
Depreciation, depletion and amortization	104,423	110,193
Depreciation, depletion and amortization	104,423	118,868
Amortization of acquired sales contracts, net	-3,696	-2,810
Capital expenditures	14,454	54,522
PRB [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Revenues	358,607	361,946
Income (loss) from operations	-4,898	15,516
Depreciation, depletion and amortization	39,245	42,227
Amortization of acquired sales contracts, net	-789	-1,199
Capital expenditures	2,094	2,157
APP [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Revenues	279,137	282,618
Income (loss) from operations	-25,728	-27,116
Depreciation, depletion and amortization	54,988	55,331
Amortization of acquired sales contracts, net	-2,974	-2,472
Capital expenditures	8,156	49,297
Other Segments [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Revenues	98,227	92,806
Income (loss) from operations	1,635	7,384
Depreciation, depletion and amortization	9,519	11,304
Amortization of acquired sales contracts, net	67	861
Capital expenditures	1,801	763
Corporate, Other and Eliminations [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Revenues	'	'
Income (loss) from operations	-44,131	-47,215
Depreciation, depletion and amortization	671	1,331
Amortization of acquired sales contracts, net	0	0
Capital expenditures	$2,403	$2,305

Segment_Information_Reconcilia

Segment Information (Reconciliation Statement Of Segment Income from Operations To Consolidated Income Before Income Taxes) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting [Abstract]	'	'
Loss from operations	($73,122)	($51,431)
Interest expense	-96,471	-95,074
Interest and investment income	1,843	2,836
Loss from continuing operations before income taxes	($167,750)	($143,669)

Supplemental_Condensed_Consoli2

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Operations) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Revenues	$735,971	$737,370
Costs, expenses and other	'	'
Cost of sales (exclusive of items shown separately below)	686,314	649,743
Depreciation, depletion and amortization	104,423	110,193
Depreciation, depletion and amortization	104,423	118,868
Amortization of acquired sales contracts, net	-3,696	-2,810
Change in fair value of coal derivatives and coal trading activities, net	914	1,308
Selling, general and administrative expenses	29,136	33,209
Other operating income, net	-7,998	-2,842
Total operating expenses	809,093	788,801
Loss from investment in subsidiaries	'	'
Loss from operations	-73,122	-51,431
Interest expense, net	'	'
Interest expense	-96,471	-95,074
Interest and investment income	1,843	2,836
Interest expense, net	-94,628	-92,238
Loss from continuing operations before income taxes	-167,750	-143,669
Provision for (benefit from) income taxes	-43,611	-59,353
Loss from continuing operations	-124,139	-84,316
Income from discontinued operations, net of tax	0	14,267
Net loss	-124,139	-70,049
Total comprehensive income (loss)	-126,769	-68,558
Parent/Issuer [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Revenues	'	'
Costs, expenses and other	'	'
Cost of sales (exclusive of items shown separately below)	3,389	2,883
Depreciation, depletion and amortization	1,472	1,406
Amortization of acquired sales contracts, net	'	'
Change in fair value of coal derivatives and coal trading activities, net	'	'
Selling, general and administrative expenses	19,944	21,698
Other operating income, net	1,593	-5,907
Total operating expenses	26,398	20,080
Loss from investment in subsidiaries	-35,347	-2,871
Loss from operations	-61,745	-22,951
Interest expense, net	'	'
Interest expense	-113,655	-110,827
Interest and investment income	7,601	9,098
Interest expense, net	-106,054	-101,729
Loss from continuing operations before income taxes	-167,799	-124,680
Provision for (benefit from) income taxes	-43,660	-59,353
Loss from continuing operations	'	-65,327
Income from discontinued operations, net of tax	'	-4,722
Net loss	-124,139	-70,049
Total comprehensive income (loss)	-126,769	-68,558
Guarantor Subsidiaries [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Revenues	735,971	737,370
Costs, expenses and other	'	'
Cost of sales (exclusive of items shown separately below)	683,775	646,860
Depreciation, depletion and amortization	102,942	108,778
Amortization of acquired sales contracts, net	-3,696	-2,810
Change in fair value of coal derivatives and coal trading activities, net	914	1,308
Selling, general and administrative expenses	7,865	10,035
Other operating income, net	-9,480	4,077
Total operating expenses	782,320	768,248
Loss from investment in subsidiaries	'	'
Loss from operations	-46,349	-30,878
Interest expense, net	'	'
Interest expense	-6,324	-6,442
Interest and investment income	17,651	15,443
Interest expense, net	11,327	9,001
Loss from continuing operations before income taxes	-35,022	-21,877
Provision for (benefit from) income taxes	'	'
Loss from continuing operations	'	-21,877
Income from discontinued operations, net of tax	'	18,989
Net loss	-35,022	-2,888
Total comprehensive income (loss)	-36,428	-3,324
Non-Guarantor Subsidiaries [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Revenues	'	'
Costs, expenses and other	'	'
Cost of sales (exclusive of items shown separately below)	'	'
Depreciation, depletion and amortization	9	9
Amortization of acquired sales contracts, net	'	'
Change in fair value of coal derivatives and coal trading activities, net	'	'
Selling, general and administrative expenses	1,803	1,476
Other operating income, net	-1,437	-1,012
Total operating expenses	375	473
Loss from investment in subsidiaries	'	'
Loss from operations	-375	-473
Interest expense, net	'	'
Interest expense	-1,050	-1,041
Interest and investment income	1,149	1,531
Interest expense, net	99	490
Loss from continuing operations before income taxes	-276	17
Provision for (benefit from) income taxes	49	'
Loss from continuing operations	'	17
Income from discontinued operations, net of tax	'	'
Net loss	-325	17
Total comprehensive income (loss)	-325	17
Eliminations [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Revenues	'	'
Costs, expenses and other	'	'
Cost of sales (exclusive of items shown separately below)	-850	'
Depreciation, depletion and amortization	'	'
Amortization of acquired sales contracts, net	'	'
Change in fair value of coal derivatives and coal trading activities, net	'	'
Selling, general and administrative expenses	-476	'
Other operating income, net	1,326	'
Total operating expenses	'	'
Loss from investment in subsidiaries	35,347	2,871
Loss from operations	35,347	2,871
Interest expense, net	'	'
Interest expense	24,558	23,236
Interest and investment income	-24,558	-23,236
Interest expense, net	'	'
Loss from continuing operations before income taxes	35,347	2,871
Provision for (benefit from) income taxes	'	'
Loss from continuing operations	'	2,871
Income from discontinued operations, net of tax	'	'
Net loss	35,347	2,871
Total comprehensive income (loss)	$36,753	$3,307

Supplemental_Condensed_Consoli3

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Balance Sheets) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'	'	'
Cash and cash equivalents	$865,761	$911,099	$730,119	$784,622
Short term investments	248,572	248,414	'	'
Receivables	274,812	229,573	'	'
Inventories	224,806	264,161	'	'
Other	123,377	128,824	'	'
Total current assets	1,737,328	1,782,071	'	'
Property, plant and equipment, net	6,616,144	6,734,286	'	'
Investment in subsidiaries	'	'	'	'
Intercompany receivables	'	'	'	'
Note receivable from Arch Western	'	'	'	'
Other	469,712	473,836	'	'
Total other assets	469,712	473,836	'	'
Total assets	8,823,184	8,990,193	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	160,361	176,142	'	'
Accrued expenses and other current liabilities	328,561	278,587	'	'
Current maturities of debt	29,950	33,493	'	'
Total current liabilities	518,872	488,222	'	'
Long-term debt	5,112,995	5,118,002	'	'
Intercompany payables	'	'	'	'
Note payable to Arch Coal	'	'	'	'
Asset retirement obligations	390,408	402,713	'	'
Accrued pension benefits	10,484	7,111	'	'
Accrued postretirement benefits other than pension	37,995	39,255	'	'
Accrued workers’ compensation	75,817	78,062	'	'
Deferred income taxes	368,057	413,546	'	'
Other noncurrent liabilities	181,866	190,033	'	'
Total liabilities	6,696,494	6,736,944	'	'
Stockholders' equity	2,126,690	2,253,249	'	'
Total liabilities and stockholders’ equity	8,823,184	8,990,193	'	'
Parent/Issuer [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	753,902	799,333	597,308	671,313
Short term investments	248,572	248,414	'	'
Receivables	33,115	14,177	'	'
Inventories	'	'	'	'
Other	80,500	84,401	'	'
Total current assets	1,116,089	1,146,325	'	'
Property, plant and equipment, net	23,765	24,851	'	'
Investment in subsidiaries	7,724,424	7,741,589	'	'
Intercompany receivables	0	'	'	'
Note receivable from Arch Western	675,000	675,000	'	'
Other	157,663	162,287	'	'
Total other assets	8,557,087	8,578,876	'	'
Total assets	9,696,941	9,750,052	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	18,326	17,781	'	'
Accrued expenses and other current liabilities	105,706	53,779	'	'
Current maturities of debt	25,481	28,882	'	'
Total current liabilities	149,513	100,442	'	'
Long-term debt	5,095,777	5,099,833	'	'
Intercompany payables	1,865,706	1,772,624	'	'
Note payable to Arch Coal	'	'	'	'
Asset retirement obligations	1,018	1,095	'	'
Accrued pension benefits	2,873	7,797	'	'
Accrued postretirement benefits other than pension	4,213	12,079	'	'
Accrued workers’ compensation	27,606	21,546	'	'
Deferred income taxes	368,057	413,546	'	'
Other noncurrent liabilities	55,522	67,841	'	'
Total liabilities	7,570,285	7,496,803	'	'
Stockholders' equity	2,126,656	2,253,249	'	'
Total liabilities and stockholders’ equity	9,696,941	9,750,052	'	'
Guarantor Subsidiaries [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	100,353	100,418	120,429	100,468
Short term investments	'	'	'	'
Receivables	16,594	23,018	'	'
Inventories	224,806	264,161	'	'
Other	42,347	43,617	'	'
Total current assets	384,100	431,214	'	'
Property, plant and equipment, net	6,592,317	6,709,398	'	'
Investment in subsidiaries	'	'	'	'
Intercompany receivables	2,079,874	1,953,719	'	'
Note receivable from Arch Western	'	'	'	'
Other	311,976	311,463	'	'
Total other assets	2,391,850	2,265,182	'	'
Total assets	9,368,267	9,405,794	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	141,921	158,224	'	'
Accrued expenses and other current liabilities	226,757	228,664	'	'
Current maturities of debt	4,469	4,611	'	'
Total current liabilities	373,147	391,499	'	'
Long-term debt	17,218	18,169	'	'
Intercompany payables	'	'	'	'
Note payable to Arch Coal	675,000	675,000	'	'
Asset retirement obligations	389,390	401,618	'	'
Accrued pension benefits	7,611	-686	'	'
Accrued postretirement benefits other than pension	33,782	27,176	'	'
Accrued workers’ compensation	48,211	56,516	'	'
Deferred income taxes	'	'	'	'
Other noncurrent liabilities	126,039	121,794	'	'
Total liabilities	1,670,398	1,691,086	'	'
Stockholders' equity	7,697,869	7,714,708	'	'
Total liabilities and stockholders’ equity	9,368,267	9,405,794	'	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	11,506	11,348	12,382	12,841
Short term investments	'	'	'	'
Receivables	229,737	197,015	'	'
Inventories	'	'	'	'
Other	530	806	'	'
Total current assets	241,773	209,169	'	'
Property, plant and equipment, net	28	37	'	'
Investment in subsidiaries	'	'	'	'
Intercompany receivables	0	-181,095	'	'
Note receivable from Arch Western	'	'	'	'
Other	73	86	'	'
Total other assets	73	-181,009	'	'
Total assets	241,874	28,197	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	114	137	'	'
Accrued expenses and other current liabilities	732	781	'	'
Current maturities of debt	'	'	'	'
Total current liabilities	846	918	'	'
Long-term debt	'	'	'	'
Intercompany payables	214,168	'	'	'
Note payable to Arch Coal	'	'	'	'
Asset retirement obligations	'	'	'	'
Accrued pension benefits	'	'	'	'
Accrued postretirement benefits other than pension	'	'	'	'
Accrued workers’ compensation	'	'	'	'
Deferred income taxes	'	'	'	'
Other noncurrent liabilities	305	398	'	'
Total liabilities	215,319	1,316	'	'
Stockholders' equity	26,555	26,881	'	'
Total liabilities and stockholders’ equity	241,874	28,197	'	'
Eliminations [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	'	'	'	'
Short term investments	'	'	'	'
Receivables	-4,634	-4,637	'	'
Inventories	'	'	'	'
Other	'	'	'	'
Total current assets	-4,634	-4,637	'	'
Property, plant and equipment, net	34	'	'	'
Investment in subsidiaries	-7,724,424	-7,741,589	'	'
Intercompany receivables	-2,079,874	-1,772,624	'	'
Note receivable from Arch Western	-675,000	-675,000	'	'
Other	'	'	'	'
Total other assets	-10,479,298	-10,189,213	'	'
Total assets	-10,483,898	-10,193,850	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	'	'	'	'
Accrued expenses and other current liabilities	-4,634	-4,637	'	'
Current maturities of debt	'	'	'	'
Total current liabilities	-4,634	-4,637	'	'
Long-term debt	'	'	'	'
Intercompany payables	-2,079,874	-1,772,624	'	'
Note payable to Arch Coal	-675,000	-675,000	'	'
Asset retirement obligations	'	'	'	'
Accrued pension benefits	'	'	'	'
Accrued postretirement benefits other than pension	'	'	'	'
Accrued workers’ compensation	'	'	'	'
Deferred income taxes	'	'	'	'
Other noncurrent liabilities	'	'	'	'
Total liabilities	-2,759,508	-2,452,261	'	'
Stockholders' equity	-7,724,390	-7,741,589	'	'
Total liabilities and stockholders’ equity	($10,483,898)	($10,193,850)	'	'

Supplemental_Condensed_Consoli4

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Cash Flows) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Cash provided by (used in) operating activities	($40,275)	$43,291
Investing Activities	'	'
Capital expenditures	-14,454	-54,522
Additions to prepaid royalties	-591	-9,142
Proceeds from disposals and divestitures	28,195	714
Purchases of short term investments	-119,176	-26,787
Proceeds from sales of short term investments	117,681	11,534
Investments in and advances to affiliates	-3,242	-4,298
Change in restricted cash	0	1,163
Cash provided by (used in) investing activities	8,413	-81,338
Financing Activities	'	'
Contributions from parent	'	'
Payments on term loan	-4,875	-4,125
Net payments on other debt	-4,521	-5,964
Debt financing costs	-1,957	'
Dividends paid	-2,123	-6,367
Transactions with affiliates, net	'	'
Cash used in financing activities	-13,476	-16,456
Increase (decrease) in cash and cash equivalents	-45,338	-54,503
Cash and cash equivalents, beginning of period	911,099	784,622
Cash and cash equivalents, end of period	865,761	730,119
Parent/Issuer [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Cash provided by (used in) operating activities	-150,338	-61,840
Investing Activities	'	'
Capital expenditures	-492	-615
Additions to prepaid royalties	'	'
Proceeds from disposals and divestitures	26,319	'
Purchases of short term investments	-119,176	-26,787
Proceeds from sales of short term investments	117,681	11,534
Investments in and advances to affiliates	-1,016	-2,043
Change in restricted cash	'	1,163
Cash provided by (used in) investing activities	23,316	-16,748
Financing Activities	'	'
Contributions from parent	'	'
Payments on term loan	-4,875	-4,125
Net payments on other debt	-4,521	-5,836
Debt financing costs	-1,957	'
Dividends paid	-2,123	-6,367
Transactions with affiliates, net	95,067	20,911
Cash used in financing activities	81,591	4,583
Increase (decrease) in cash and cash equivalents	-45,431	-74,005
Cash and cash equivalents, beginning of period	799,333	671,313
Cash and cash equivalents, end of period	753,902	597,308
Guarantor Subsidiaries [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Cash provided by (used in) operating activities	142,978	120,755
Investing Activities	'	'
Capital expenditures	-13,962	-53,907
Additions to prepaid royalties	-591	-9,142
Proceeds from disposals and divestitures	1,876	714
Purchases of short term investments	'	'
Proceeds from sales of short term investments	'	'
Investments in and advances to affiliates	-2,226	-2,383
Change in restricted cash	'	'
Cash provided by (used in) investing activities	-14,903	-64,718
Financing Activities	'	'
Contributions from parent	'	128
Payments on term loan	'	0
Net payments on other debt	'	-128
Debt financing costs	'	'
Dividends paid	'	'
Transactions with affiliates, net	-128,140	-36,076
Cash used in financing activities	-128,140	-36,076
Increase (decrease) in cash and cash equivalents	-65	19,961
Cash and cash equivalents, beginning of period	100,418	100,468
Cash and cash equivalents, end of period	100,353	120,429
Non-Guarantor Subsidiaries [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Cash provided by (used in) operating activities	-32,915	-15,624
Investing Activities	'	'
Capital expenditures	'	'
Additions to prepaid royalties	'	'
Proceeds from disposals and divestitures	'	'
Purchases of short term investments	'	'
Proceeds from sales of short term investments	'	'
Investments in and advances to affiliates	'	'
Change in restricted cash	'	'
Cash provided by (used in) investing activities	'	'
Financing Activities	'	'
Contributions from parent	'	'
Payments on term loan	'	'
Net payments on other debt	'	'
Debt financing costs	'	'
Dividends paid	'	'
Transactions with affiliates, net	33,073	15,165
Cash used in financing activities	33,073	15,165
Increase (decrease) in cash and cash equivalents	158	-459
Cash and cash equivalents, beginning of period	11,348	12,841
Cash and cash equivalents, end of period	11,506	12,382
Eliminations [Member]	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Cash provided by (used in) operating activities	'	'
Investing Activities	'	'
Capital expenditures	'	'
Additions to prepaid royalties	'	'
Proceeds from disposals and divestitures	'	'
Purchases of short term investments	'	'
Proceeds from sales of short term investments	'	'
Investments in and advances to affiliates	'	128
Change in restricted cash	'	'
Cash provided by (used in) investing activities	'	128
Financing Activities	'	'
Contributions from parent	'	-128
Payments on term loan	'	'
Net payments on other debt	'	'
Debt financing costs	'	'
Dividends paid	'	'
Transactions with affiliates, net	'	'
Cash used in financing activities	'	-128
Increase (decrease) in cash and cash equivalents	'	'
Cash and cash equivalents, beginning of period	'	'
Cash and cash equivalents, end of period	'	'