Arch Resources (ARCH) 10-Q 12 Nov 13 2013 Q3 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	9 Months Ended
	Sep. 30, 2013	Nov. 04, 2013
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'ARCH COAL INC	'
Entity Central Index Key	'0001037676	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	212,279,999

Consolidated_Statements_Of_Ope

Consolidated Statements Of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]	'	'	'	'
Revenues	$791,269	$975,170	$2,294,971	$2,901,092
Costs and Expenses [Abstract]	'	'	'	'
Cost of sales (exclusive of items shown separately below)	688,712	808,489	1,994,653	2,414,306
Depreciation, depletion and amortization	106,323	118,942	327,601	374,631
Amortization of acquired sales contracts, net	-2,568	-4,093	-7,587	-22,561
Change in fair value of coal derivatives and coal trading activities, net	9,753	5,840	2,053	-29,827
Asset impairment and mine closure costs	200,397	-2,144	220,879	523,439
Goodwill impairment	'	'	'	115,791
Legal contingencies	'	-79,532	'	-79,532
Selling, general and administrative expenses	28,800	33,266	96,311	99,305
Other operating income, net	-5,395	-24,840	-16,476	-44,606
Total operating expenses	1,026,022	855,928	2,617,434	3,350,946
Income (loss) from operations	-234,753	119,242	-322,463	-449,854
Interest expense, net	'	'	'	'
Interest expense	-95,624	-75,710	-285,454	-229,210
Interest and investment income	697	1,459	4,749	3,568
Interest expense, net	-94,927	-74,251	-280,705	-225,642
Other nonoperating expense:	'	'	'	'
Net loss resulting from early retirement and refinancing of debt	'	'	'	-19,042
Loss from continuing operations before income taxes	-329,680	44,991	-603,168	-694,538
Provision for (benefit from) income taxes	-121,913	20,318	-230,734	-262,656
Income (loss) from continuing operations	-207,767	24,673	-372,434	-431,882
Income from discontinued operations, including gain on sale - net of tax	79,404	21,078	101,816	43,618
Net income (loss)	-128,363	45,751	-270,618	-388,264
Less: Net income attributable to noncontrolling interest	'	'	'	-268
Net income (loss) attributable to Arch Coal, Inc.	($128,363)	$45,751	($270,618)	($388,532)
Earnings (loss) per common share	'	'	'	'
Income (Loss) from Continuing Operations, Per Basic Share	($0.98)	$0.12	($1.76)	($2.04)
Income (Loss) from Continuing Operations, Per Diluted Share	($0.98)	$0.12	($1.76)	($2.04)
Basic earnings (loss) per common share	($0.61)	$0.22	($1.28)	($1.83)
Diluted earnings (loss) per common share	($0.61)	$0.22	($1.28)	($1.83)
Weighted average shares outstanding	'	'	'	'
Basic, weighted average shares outstanding	212,111	212,053	212,085	211,931
Diluted, weighted average shares outstanding	212,111	212,076	212,085	211,931
Dividends declared per common share	$0.03	$0.03	$0.09	$0.17

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Loss) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'	'	'
Net income (loss)	($128,363)	$45,751	($270,618)	($388,264)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	1,346	-439	-224	10,586
Derivatives Qualifying as Hedges, Tax benefit	-486	157	82	-3,810
Derivatives Qualifying as Hedges, Adjustment, Net of Tax	860	-282	-142	6,776
Pension and Other Postretirement Benefit Plans, Total comprehensive income (loss) before tax	1,277	-989	4,981	-5,957
Pension and Other Postretirement Benefit Plans, Tax impact	-458	374	-1,791	2,162
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	819	-615	3,190	-3,795
Available-for-sale Securities Adjustment, Total comprehensive income (loss) before tax	1,136	-869	7,648	-377
Available-for-sale Securities, Tax benefit	-448	314	-2,795	137
Available-for-sale Securities Adjustment, Net of Tax	688	-555	4,853	-240
Total other comprehensive income (loss)	2,367	-1,452	7,901	2,741
Total comprehensive income (loss)	($125,996)	$44,299	($262,717)	($385,523)

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$1,133,128	$784,622
Restricted cash	'	3,453
Short term investments	248,724	234,305
Trade accounts receivable	190,723	247,539
Other receivables	24,116	84,541
Inventories	287,409	365,424
Prepaid royalties	8,350	11,416
Deferred income taxes	67,381	67,360
Coal derivative assets	22,836	22,975
Other current assets	46,972	92,469
Total current assets	2,029,639	1,914,104
Property, plant and equipment, net	6,778,225	7,337,098
Other assets	'	'
Prepaid royalties	85,001	87,773
Goodwill	265,423	265,423
Equity investments	223,554	242,215
Other noncurrent assets	149,613	160,164
Total other assets	723,591	755,575
Total assets	9,531,455	10,006,777
Current liabilities	'	'
Accounts payable	207,273	224,418
Coal derivative liabilities	421	1,737
Accrued expenses and other current liabilities	349,033	318,018
Current maturities of debt	23,050	32,896
Total current liabilities	579,777	577,069
Long-term debt	5,074,384	5,085,879
Asset retirement obligations	411,121	409,705
Accrued pension benefits	68,539	67,630
Accrued postretirement benefits other than pension	44,279	45,086
Accrued workers’ compensation	82,014	81,629
Deferred income taxes	484,130	664,182
Other noncurrent liabilities	205,557	221,030
Total liabilities	6,949,801	7,152,210
Stockholders' equity	'	'
Common stock, $0.01 par value, authorized 260,000 shares, issued 213,792 and 213,759 shares at September 30, 2013 and December 31, 2012	2,141	2,141
Paid-in capital	3,035,732	3,026,823
Treasury stock, at cost	-53,848	-53,848
Accumulated deficit	-393,765	-104,042
Accumulated other comprehensive loss	-8,606	-16,507
Total stockholders’ equity	2,581,654	2,854,567
Total liabilities and stockholders’ equity	$9,531,455	$10,006,777

Balance_Sheet_Parenthetical_Pa

Balance Sheet Parenthetical (Parentheticals) (USD $)	Sep. 30, 2013	Dec. 31, 2012
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	213,759,000

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Operating activties	'	'
Net income (loss)	($270,618)	($388,264)
Adjustments to reconcile net loss to cash provided by operating activities:	'	'
Depreciation, depletion and amortization	348,863	399,672
Amortization of acquired sales contracts, net	-7,587	-22,561
Amortization relating to financing activities	18,525	14,345
Prepaid royalties expensed	11,973	19,802
Employee stock-based compensation expense	8,909	9,435
Asset impairment and noncash mine closure costs	220,879	501,942
Amortization of premiums on debt securities held	3,679	'
Gain on sale of Canyon Fuel	-115,679	'
Goodwill impairment	'	115,791
Net loss resulting from early retirement of debt and financing activities	'	19,042
Changes in:	'	'
Receivables	72,436	102,252
Inventories	21,387	-16,635
Coal derivative assets and liabilities	-1,568	-29,523
Accounts payable, accrued expenses and other current liabilities	19,287	-51,968
Income taxes, net	787	22,048
Deferred income taxes	184,418	255,530
Other	39,737	-83,453
Cash provided by operating activities	186,592	356,395
Investing activities	'	'
Capital expenditures	-223,168	-303,968
Minimum royalty payments	-10,901	-9,192
Proceeds from dispositions of property, plant and equipment	8,799	22,624
Proceeds from sale-leaseback transactions	34,919	'
Proceeds from sale of Canyon Fuel	422,663	'
Purchases of short term investments	-85,418	-99,628
Proceeds from sales of short term investments	67,255	'
Investments in and advances to affiliates	-11,124	-12,685
Purchase of noncontrolling interest	'	-17,500
Change in restricted cash	3,453	6,872
Cash provided by (used in) investing activities	206,478	-413,477
Financing activities	'	'
Proceeds from issuance of term loan	'	1,386,000
Payments on term loan	-12,375	-3,500
Payments to retire debt	-384	-452,806
Net decrease in borrowings under lines of credit	'	-381,300
Net payments on other debt	-12,700	-13,078
Debt financing costs	'	-34,686
Dividends paid	-19,105	-36,072
Proceeds from exercise of options under incentive plans	'	5,131
Cash provided by (used in) financing activities	-44,564	469,689
Increase in cash and cash equivalents	348,506	412,607
Cash and cash equivalents, beginning of period	784,622	138,149
Cash and cash equivalents, end of period	$1,133,128	$550,756

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	'
	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. In addition, the Company is developing a metallurgical coal mine in West Virginia. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation.
	The Company completed the sale of a subsidiary comprised of three mining complexes in the Western Bituminous reportable segment ("WBIT") on August 16, 2013. The results of these mining complexes have been segregated from continuing operations and are reflected, net of tax, as discontinued operations in the condensed consolidated statements of operations for all periods presented. See further discussion in Note 3, "Discontinued Operations".
	In response to decreasing demand for thermal coal in Appalachia, the Company closed four mining complexes, temporarily idled a fifth complex, and curtailed production at other mines in the region in the second quarter of 2012. The operations continued to ship from inventory into the third quarter of 2012. The results for the closed and idled complexes are reflected in continuing operations in the condensed consolidating statements of operations for the three and nine month periods ended September 30, 2012. See further discussion in Note 5, "Impairment Charges".
	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 and nine month periods ended September 30, 2013 are not necessarily indicative of results to be expected for the year ending December 31, 2013. 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, 2012 included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.

Accounting_Policies_Accounting

Accounting Policies Accounting Policies	9 Months Ended
	Sep. 30, 2013
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.

Discontinued_Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	'
	Discontinued Operations
	As part of a strategy to divest its non-core thermal coal assets, the Company entered into a definitive agreement on June 27, 2013 to sell Canyon Fuel Company, LLC (Canyon Fuel), to Bowie Resources, LLC. Canyon Fuel operated two longwall mining complexes and a continuous miner operation in Utah. The sale was completed on August 16, 2013, for $422.7 million in cash, including adjustments to initial working capital estimates. The purchase price is subject to final working capital adjustments, which we do not expect to have a significant impact on our results of operations or liquidity.
	The following table summarizes the results of discontinued operations:
		Three Months Ended September 30,					Nine Months Ended September 30,
		2013		2012			2013		2012
		(In thousands)
	Total Revenues	$	45,763	$	112,448		$	219,002	$	289,715
	Income from discontinued operations before income taxes	$	3,429	$	16,718		$	32,166	$	50,911
	Gain on sale	115,679		—			115,679		—
	Income tax expense (benefit)	39,704		(4,360		)	46,029		7,293
	Income from discontinued operations, including gain on sale - net of tax	$	79,404	$	21,078		$	101,816	$	43,618
	Basic earnings per common share from discontinued operations	$	0.37	$	0.1		$	0.48	$	0.21
	Diluted earnings per common share from discontinued operations	$	0.37	$	0.1		$	0.48	$	0.21

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Abstract]	'
Comprehensive Income (Loss) Note [Text Block]	'
	Accumulated Other Comprehensive Loss
	Other comprehensive loss includes transactions recorded in stockholders' equity during the year, excluding net income and transactions with stockholders. In February 2013, the FASB issued ASU 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income. The standard requires that companies present, either parenthetically on the face of the financial statements or in a single note, the effect of significant amounts reclassified from each component of accumulated other comprehensive income and the income statement line items affected by the reclassification. The Company adopted the provisions of the new guidance in the first quarter of 2013.
	The following items are included in accumulated other comprehensive loss:
						Pension,
						Postretirement
						and Other							Accumulated
						Post-							Other
		Derivative				Employment				Available-for-			Comprehensive
		Instruments				Benefits				Sale Securities			Loss
		(In thousands)
	Balance at December 31, 2012	$	2,244			$	(18,286	)		$	(465	)	$	(16,507	)
	Unrealized gains	1,197				1,938				4,653			7,788
	Amounts reclassified from accumulated other comprehensive income	(1,339		)		1,252				200			113
	Balance at September 30, 2013	$	2,102			$	(15,096	)		$	4,388		$	(8,606	)
	The following amounts were reclassified out of accumulated other comprehensive loss:
			Amount Reclassified from
			Accumulated Comprehensive Loss								Line Item in the
	Details about accumulated other		Three Months Ended				Nine Months Ended				Condensed Consolidated
	comprehensive income components		30-Sep-13				30-Sep-13				Statement of Operations
			(In thousands)
	Derivative instruments		$	692			$	2,093			Revenues
			(249		)		(754		)		Provision for (benefit from) income taxes
			$	443			$	1,339			Net of tax
	Pension, postretirement and other post-employment benefits
	Amortization of prior service credits		$	5,573			$	11,154		1
	Amortization of actuarial gains (losses), net		(3,823		)		(13,108		)	1
			1,750				(1,954		)		Total before tax
			(631		)		702				Provision for (benefit from) income taxes
			$	1,119			$	(1,252	)		Net of tax
	Available-for-sale securities		$	(4	)		$	(313	)	2	Interest and investment income
			2				113				Provision for (benefit from) income taxes
			$	(2	)		$	(200	)		Net of tax
	1 Production-related benefits and workers' compensation costs are included in costs to produce coal. See Note 14, "Workers' Compensation Expense" and Note 15 "Employee Benefit Plans" for more information about pension, postretirement and postemployment benefit costs.
	2 The gains and losses on sales of available-for-sale-securities are determined on a specific identification basis.

Impairment_Charges

Impairment Charges	9 Months Ended
	Sep. 30, 2013
Impairment charges [Abstract]	'
Asset Impairment Charges [Text Block]	'
	Impairment charges
	Weak thermal coal markets in Appalachia are expected to persist longer than the Company previously anticipated, which caused the Company to assess in the third quarter of 2013 whether the carrying values of certain assets were recoverable through future cash flows. The Company determined that the carrying amounts of certain assets associated with the Hazard mining complex in Kentucky and the Company's ADDCAR subsidiary, which manufactures and sells its patented highwall mining system, could not be recovered through future cash flows expected to be generated from use of the assets and their ultimate disposal.
	The assets' fair values were determined based on projections of cash flows to be generated from use of the assets and their ultimate disposal including estimates relating to market demand, coal prices, production costs and mine plans, and recovery value of the assets. An impairment loss of $142.8 million was recognized to write the carrying value of the assets to their fair value of $71.3 million. These losses are reflected on the line "Asset impairment and mine closure costs" in the condensed consolidated statements of operations.
	During the third quarter of 2013, the Company also recognized an other-than-temporary impairment of an equity method investment. See further discussion in Note 8, "Equity Method Investments and Membership Interests in Joint Ventures."
	In the second quarter of 2012, the closure and idling of mines in Appalachia discussed in Note 1, "Basis of Presentation" resulted in closure costs and impairment charges of $523.4 million that are reflected on the line "Asset impairment and mine closures costs" in the condensed consolidated statements of operations.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories consist of the following:
		30-Sep		31-Dec
		2013		2012
		(In thousands)
	Coal	$	134,481	$	180,917
	Repair parts and supplies	143,763		172,139
	Work-in-process	9,165		12,368
		$	287,409	$	365,424
	The repair parts and supplies are stated net of an allowance for slow-moving and obsolete inventories of $8.8 million at September 30, 2013 and $13.6 million at December 31, 2012.

Investments_in_AvailableforSal

Investments in Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2013
Available-for-sale Securities [Abstract]	'
Available-for-sale Securities [Text Block]	'
	. 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:
		September 30, 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	$	123,809	$	7	$	(126	)	$	123,690	$	123,690	$	—
	Corporate notes and bonds	125,479		21		(466		)	125,034		125,034		—
	Equity securities	5,271		10,284		(2,865		)	12,690		—		12,690
	Total Investments	$	254,559	$	10,312	$	(3,457	)	$	261,414	$	248,724	$	12,690
		December 31, 2012
											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	$	146,993	$	2	$	(412	)	$	146,583	$	146,583	$	—
	Corporate notes and bonds	88,118		—		(396		)	87,722		87,722		—
	Equity securities	5,271		2,704		(2,628		)	5,347		—		5,347
	Total Investments	$	240,382	$	2,706	$	(3,436	)	$	239,652	$	234,305	$	5,347
	The aggregate fair value of investments with unrealized losses that have been owned for less than a year was $167.5 million and $223.3 million at September 30, 2013 and December 31, 2012, respectively. The aggregate fair value of investments with unrealized losses that have been owned for over a year was $51.6 million and $0.4 million at September 30, 2013 and December 31, 2012, respectively.
	The debt securities outstanding at September 30, 2013 have maturity dates ranging from the fourth quarter of 2013 through the first 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.

Equity_Investments_And_Members

Equity Investments And Membership Interests In Joint Ventures	9 Months Ended
	Sep. 30, 2013
Equity Method Investments and Joint Ventures [Abstract]	'
Equity Investments and Membership Interests in Joint Ventures	'
	Equity Method Investments and Membership Interests in Joint Ventures
	The Company accounts for its investments and membership interests in joint ventures under the equity method of accounting if the Company has the ability to exercise significant influence, but not control, over the entity. Below are the equity method investments reflected in the condensed consolidated balance sheets:
	In thousands	Knight Hawk			DKRW			DTA			Tenaska			Millennium			Tongue River			Total
	Balance at December 31, 2012	$	149,063		$	15,515		$	15,462		$	15,264		$	32,214		$	14,697		$	242,215
	Advances to (distributions from) affiliates, net	(5,342		)	—			2,537			—			4,954			2,696			4,845
	Equity in comprehensive income (loss)	13,362			(1,832		)	(3,855		)	—			(1,953		)	(281		)	5,441
	Impairment of equity investment	—			(13,683		)	—			(15,264		)	—			—			(28,947		)
	Balance at September 30, 2013	$	157,083		$	—		$	14,144		$	—		$	35,215		$	17,112		$	223,554
	Equity method investments are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the investments may not be recoverable. Certain of the Company's investments are in development stage companies whose success depends on factors including receipt of permits and other regulatory environment issues, the ability of the investee companies to raise additional funds in financial markets that can be volatile, and other key business factors.
	During the second quarter of 2013, Tenaska Trailblazer Partners, LLC ("Tenaska") announced that it was discontinuing its development plans for the Trailblazer Energy Center in Texas. As a result, the Company recorded a $20.5 million impairment charge, which consisted of its 35% equity investment of $15.3 million and a $5.2 million receivable balance related to reimbursements for development work.
	DKRW Advanced Fuels, LLC ("DKRW") had previously entered into an Engineering, Procurement and Construction Agreement with a Chinese company to construct and commission the Medicine Bow coal-to-liquids facility. The project did not progress to the next stage of development, and the Company recorded an other-than-temporary impairment charge of $57.7 million in the third quarter of 2013, which includes the Company's 24% equity investment of $13.7 million and a $44.0 million loan receivable balance. The impairment charges are included on the line "Asset impairment and mine closure costs" in the condensed consolidated statement of operations.
	The Company may be required to make future contingent payments of up to $58.5 million related to development financing for certain of its equity investees. The Company’s obligation to make these payments, as well as the timing of any payments required, is contingent upon the achievement of project development milestones, which can be affected by the factors named above.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2013
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 2013. 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 September 30, 2013, the Company had protected the price of approximately 94% of its expected purchases for the remainder of 2013 and 82% of its expected 2014 purchases. At September 30, 2013, the Company had purchased heating oil call options for approximately 65 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 September 30, 2013, the Company held heating oil call options for 2.8 million gallons that will settle in the remainder of 2013 and 3.8 million gallons that will settle ratably in 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 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 September 30, 2013, the Company held derivatives for risk management purposes that are expected to settle in the following years:
	(Tons in thousands)		2013			2014			2015			Total
	Coal sales		2,314			4,458			780			7,552
	Coal purchases		609			1,260			—			1,869
	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 $0.4 million of gains in the remainder of 2013 and $7.0 million of gains in 2014.
	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:
			30-Sep-13											31-Dec-12
	Fair Value of Derivatives		Asset				Liability							Asset			Liability
	(In thousands)		Derivative				Derivative							Derivative			Derivative
	Derivatives Designated as Hedging Instruments
	Coal		$	3,009			$	(4	)					$	3,277		$	(10	)
	Derivatives Not Designated as Hedging Instruments
	Heating oil -- diesel purchases		3,825				—							7,379			—
	Heating oil -- fuel surcharges		400				—							1,961			—
	Coal -- held for trading purposes		59,789				(52,383		)					17,403			(16,933		)
	Coal -- risk management		15,907				(3,903		)					24,843			(7,342		)
	Total		79,921				(56,286		)					51,586			(24,275		)
	Total derivatives		82,930				(56,290		)					54,863			(24,285		)
	Effect of counterparty netting		(55,869		)		55,869							(22,548		)	22,548
	Net derivatives as classified in the balance sheets		$	27,061			$	(421	)		$	26,640		$	32,315		$	(1,737	)	$	30,578
					30-Sep-13				31-Dec-12
	Net derivatives as reflected on the balance sheets
	Heating oil		Other current assets		$	4,225			$	9,340
	Coal		Coal derivative assets		22,836				22,975
			Coal derivative liabilities		(421		)		(1,737		)
					$	26,640			$	30,578
	The Company had a current liability for the obligation to post cash collateral of $4.9 million at September 30, 2013 and a current asset for the right to reclaim cash collateral of $16.2 million at December 31, 2012. These amounts are not included with the derivatives presented in the table above and are included in "accrued expenses and other current liabilities" and “other current assets”, respectively, 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 September 30,
			Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)								Gains (Losses) Reclassified from Other Comprehensive Income into Income
											(Effective Portion)
			2013				2012				2013			2012
	Coal sales	(1)	$	3,132			$	259			$	911		$	542
	Coal purchases	(2)	(942		)		(178		)		(123		)	—
	Totals		$	2,190			$	81			$	788		$	542
	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 September 30, 2013 and 2012.
	Derivatives Not Designated as Hedging Instruments (in thousands)
	For the three months ended September 30,
			Gain (Loss) Recognized
			2013				2012
	Coal — unrealized	(3)	$	(10,668	)		$	(11,328	)
	Coal — realized	(4)	$	9,929			$	14,072
	Heating oil — diesel purchases	(4)	$	(288	)		$	5,184
	Heating oil — fuel surcharges	(4)	$	(222	)		$	1,092
	____________________________________________________________
	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
	Derivatives used in Cash Flow Hedging Relationships (in thousands)
	For the nine months ended September 30
			Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)								Gains (Losses) Reclassified from Other Comprehensive Income into Income
(Effective Portion)
		2013				2012				2013			2012
Coal sales	(1)	$	2,308			$	4,983			$	2,822		$	1,552
Coal purchases	(2)	(511		)		(1,122		)		(633		)	—
Totals		$	1,797			$	3,861			$	2,189		$	1,552
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 nine month periods ended September 30, 2013 and 2012.
Derivatives Not Designated as Hedging Instruments (in thousands)
For the nine months ended September 30
		Gain (Loss) Recognized
		2013				2012
Coal — unrealized	(3)	$	(5,089	)		$	23,670
Coal — realized	(4)	$	25,725			$	25,901
Heating oil — diesel purchases	(4)	$	(9,760	)		$	(16,902	)
Heating oil — fuel surcharges	(4)	$	(817	)		$	(1,140	)
____________________________________________________________
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 $0.9 million and $5.5 million during the three months ended September 30, 2013 and 2012, respectively, related to its trading portfolio. The Company recognized net unrealized and realized gains of $3.0 million and $6.2 million during the nine months ended September 30, 2013 and 2012, respectively, 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 September 30, 2013, gains on derivative contracts designated as hedge instruments in cash flow hedges of approximately $2.9 million are expected to be reclassified from other comprehensive income into earnings during the next twelve months.

Debt

Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Debt	'
	Debt
		September 30,		December 31,
		2013		2012
		(In thousands)
	Term loan ($1.63 billion face value) due 2018	$	1,617,097	$	1,627,384
	8.75% senior notes ($600.0 million face value) due 2016	592,646		590,999
	7.00% senior notes due 2019 at par	1,000,000		1,000,000
	9.875% senior notes ($375.0 million face value) due 2019	361,779		360,042
	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	25,912		40,350
		5,097,434		5,118,775
	Less current maturities of debt	23,050		32,896
	Long-term debt	$	5,074,384	$	5,085,879
	At September 30, 2013, the available borrowing capacity under the Company's lines of credit was approximately $204.0 million.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2013
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 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 September 30, 2013.
	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:
		Fair Value at September 30, 2013
		Total			Level 1			Level 2		Level 3
		(In thousands)
	Assets:
	Investments in marketable securities	$	261,414		$	101,338		$	160,076	$	—
	Derivatives	27,061			22,750			—		4,311
	Total assets	$	288,475		$	124,088		$	160,076	$	4,311
	Liabilities:
	Derivatives	$	421		$	—		$	204	$	217
	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 September 30, 2013			Nine Months Ended September 30, 2013
		(In thousands)
	Balance, beginning of period	$	3,438		$	8,174
	Realized and unrealized losses recognized in earnings, net	(570		)	(9,882		)
	Purchases	1,464			7,317
	Issuances	—			(25		)
	Settlements	(238		)	(1,490		)
	Ending balance	$	4,094		$	4,094
	Net unrealized losses during the three and nine month periods ended September 30, 2013 related to level 3 financial instruments held on September 30, 2013 were $0.2 million and $4.8 million, respectively.
	Fair Value of Long-Term Debt
	At September 30, 2013 and December 31, 2012, the fair value of the Company’s debt, including amounts classified as current, was $4.5 billion and $5.0 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.

Accrued_Expenses_and_Other_Cur

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2013
Accrued Expenses and Other Current Liabilities [Abstract]	'
Accounts Payable and Accrued Liabilities Disclosure [Text Block]	'
	Accrued Expenses and Other Current Liabilities
	Accrued expenses and other current liabilities consist of the following:
		September 30,		December 31,
		2013		2012
		(In thousands)
	Payroll and employee benefits	$	68,245	$	72,405
	Taxes other than income taxes	113,872		121,029
	Interest	80,454		42,413
	Acquired sales contracts	14,461		14,038
	Workers’ compensation	12,215		10,371
	Asset retirement obligations	38,895		38,920
	Other	20,891		18,842
		$	349,033	$	318,018

StockBased_Compensation_And_Ot

Stock-Based Compensation And Other Incentive Plans	9 Months Ended
	Sep. 30, 2013
Share-based Compensation [Abstract]	'
Stock-Based Compensation And Other Incentive Plans	'
	Stock-Based Compensation and Other Incentive Plans
	The Company granted options to purchase approximately 2.0 million shares of common stock during the nine months ended September 30, 2013. The weighted average exercise price of the options was $5.23 per share and the weighted average grant date fair value was $2.37 per share. The options’ fair value was determined using the Black-Scholes option pricing model, using a weighted average risk-free rate of 0.65%, a weighted average dividend yield of 2.30% and a weighted average volatility of 66.74%. The options’ expected life is 4.5 years and the options vest ratably over three years and provide for the continuation of vesting after retirement for recipients that meet certain criteria. The expense for these options will be recognized through the date that the employee first becomes eligible to retire and is no longer required to provide service to earn all or part of the award.
	During the nine months ended September 30, 2013, the Company also granted restricted stock units totaling 969,100 shares whose grant date fair value was $5.20 per share. The shares vest at the end of three years.
	The Company has a long-term incentive program that allows for the award of performance units. The total number of units earned by a participant is based on financial and operational performance measures, and may be paid out in cash or in shares of the Company’s common stock. The Company recognizes compensation expense over the three-year term of the grant. Amounts accrued and unpaid for all grants under the plan totaled $15.0 million and $13.1 million as of September 30, 2013 and December 31, 2012, respectively.

Workers_Compensation_Expense

Workers' Compensation Expense	9 Months Ended
	Sep. 30, 2013
Workers' Compensation Expense [Abstract]	'
Workers' Compensation Expense	'
	Workers’ Compensation Expense
	The following table details the components of workers’ compensation expense:
		Three Months Ended September 30,				Nine Months Ended September 30,
		2013		2012		2013		2012
		(In thousands)
	Service cost	$	363	$	419	$	1,373	$	1,458
	Interest cost	709		629		2,022		1,708
	Net amortization	262		—		731		(574		)
	Curtailments	816		—		816		1,933
	Total occupational disease	2,150		1,048		4,942		4,525
	Traumatic injury claims and assessments	4,114		7,453		16,263		19,052
	Total workers’ compensation expense	$	6,264	$	8,501	$	21,205	$	23,577

Employee_Benefit_Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2013
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 September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
		(In thousands)
	Service cost	$	6,672		$	6,156		$	21,162		$	21,062
	Interest cost	3,994			3,683			11,796			11,755
	Curtailments	47			—			47			324
	Expected return on plan assets	(5,848		)	(5,508		)	(17,690		)	(16,523		)
	Amortization of prior service costs (credits)	(51		)	273			(152		)	200
	Amortization of other actuarial losses	3,617			3,248			12,430			11,019
	Net benefit cost	$	8,431		$	7,852		$	27,593		$	27,837
	The following table details the components of other postretirement benefit costs (credits):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
		(In thousands)
	Service cost	$	497		$	541		$	1,591		$	1,629
	Interest cost	427			508			1,273			1,519
	Curtailments	(5,444		)	(2,212		)	(5,444		)	(4,049		)
	Amortization of prior service credits	(2,641		)	(2,837		)	(8,121		)	(8,708		)
	Amortization of other actuarial losses (gains)	(55		)	(130		)	(53		)	(391		)
	Net benefit credit	$	(7,216	)	$	(4,130	)	$	(10,754	)	$	(10,000	)
	A curtailment was triggered in the third quarter of 2013 by reductions in employees' expected years of future service resulting primarily from the sale of Canyon Fuel.  Curtailments include the recognition of unamortized prior service costs and actuarial adjustments to the respective projected benefit obligations for the cash balance pension and medical plans and pneumoconiosis benefits.

Earnings_Per_Common_Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings Per Common Share	'
	. Earnings (Loss) Per Common Share
	The effect of options, restricted stock and restricted stock units equaling 7.0 million and 5.8 million shares of common stock were excluded from the calculation of diluted weighted average shares outstanding for the three month periods ended September 30, 2013 and 2012, respectively, and 7.9 million and 5.0 million shares were excluded for the nine month periods ended September 30, 2013 and 2012, 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 and nine month periods ended September 30, 2013 and the nine months ended September 30,2012 were not significant.

Settlement_with_Patriot_Coal

Settlement with Patriot Coal	9 Months Ended
	Sep. 30, 2013
Settlement with Patriot Coal [Abstract]	'
Legal Matters and Contingencies [Text Block]	'
	Settlement with Patriot Coal
	On December 31, 2005, Arch entered into a purchase and sale agreement to sell mining complexes to Magnum Coal Company ("Magnum"). On July 23, 2008, Patriot Coal Corporation acquired Magnum from Arc Light Capital Partners. On July 9, 2012, Patriot Coal Corporation and certain of its wholly owned subsidiaries, including Magnum, (collectively, "Patriot") filed voluntary petitions for reorganization under Chapter 11 of the U.S. Code in the U.S. Bankruptcy Court for the Southern District of New York.
	The Company entered into a settlement agreement with Patriot on October, 10, 2013 that resolves all pending and potential legal claims with Patriot stemming from the sale of coal companies to Magnum and the subsequent purchase of those companies by Patriot in 2008.
	The Company will pay $5.0 million in cash to Patriot upon its exit from bankruptcy, which is reflected in "Other operating income, net" in the condensed consolidated statement of operations for the three month and nine month periods ended September 30, 2013. Additionally, the settlement includes the release of a $16.7 million letter of credit posted by Patriot in the Company's favor for surety bonds related to the companies sold to Magnum. The Company has also agreed to purchase Patriot's Guffey reserves for $16.0 million in cash upon their exit from bankruptcy. The Guffey reserves border the Company's Leer metallurgical coal development.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
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, but no hearing dates have been set at this time.
	In addition, the Company is a party to numerous claims and lawsuits with respect to various matters. As of September 30, 2013 and December 31, 2012, the Company had accrued $21.2 million and $32.8 million, respectively, for all legal matters, including $7.7 million and $4.4 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	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Segment Reporting Disclosure [Text Block]	'
	Segment Information
	The Company has three reportable business segments, which are based on the major coal producing basins in which the Company operates. Each of these reportable business segments includes a number of mine complexes. The Company manages its coal sales by coal basin, not by individual mine complex. Geology, coal transportation routes to customers, regulatory environments and coal quality or type are characteristic to a basin. Accordingly, market and contract pricing have developed by coal basin. Mine 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; the WBIT segment, with operations in Colorado; the Appalachia (APP) segment, with operations in West Virginia, Kentucky, Maryland and Virginia.  The “Other” operating segment includes primarily the Company’s Illinois operations and ADDCAR.
	Operating segment results for the three and nine months ended September 30, 2013 and 2012 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. 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 for the WBIT segment for all periods presented reflect only continuing operations, since Canyon Fuel results 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. Goodwill is allocated to the respective reporting units, even though it may not be reflected in the subsidiaries’ financial statements. Asset balances for the WBIT segment as of September 30, 2012 include the Canyon Fuel assets. Prior year asset amounts have been restated to reflect a change in how certain unassigned coal reserves and goodwill amounts are presented.
		PRB			APP			WBIT			Other			Corporate,			Consolidated
											Operating			Other and
											Segments			Eliminations
		(in thousands)
	Three months ended September 30, 2013
	Revenues	$	420,521		$	263,188		$	78,022		$	29,538		$	—		$	791,269
	Income (loss) from operations	20,694			(157,883		)	9,287			(9,231		)	(97,620		)	(234,753		)
	Depreciation, depletion and amortization	46,619			46,529			9,436			2,523			1,216			106,323
	Amortization of acquired sales contracts, net	(864		)	(2,691		)	—			987			—			(2,568		)
	Asset impairment and mine closure costs	—			126,449			—			16,280			57,668			200,397
	Capital expenditures	1,695			44,624			5,859			1,263			663			54,104
	Three months ended September 30, 2012
	Revenues	$	406,719		$	436,409		$	105,515		$	26,527		$	—		$	975,170
	Income (loss) from operations	38,873			88,695			24,110			(1,298		)	(31,138		)	119,242
	Depreciation, depletion and amortization	43,944			61,596			9,985			2,594			823			118,942
	Amortization of acquired sales contracts, net	(589		)	(3,711		)	—			207			—			(4,093		)
	Asset impairment and mine closure costs	—			(1,801		)	—			(210		)	(133		)	(2,144		)
	Capital expenditures	5,620			77,772			13,510			3,640			1,353			101,895
	Nine months ended September 30, 2013
	Revenues	$	1,135,892		$	883,484		$	187,374		$	88,221		$	—		$	2,294,971
	Income (loss) from operations	53,244			(190,278		)	23,766			(407		)	(208,788		)	(322,463		)
	Depreciation, depletion and amortization	130,993			157,866			26,528			7,792			4,422			327,601
	Amortization of acquired sales contracts, net	(3,004		)	(7,975		)	—			3,392			—			(7,587		)
	Asset impairment and mine closure costs	—			126,449			—			16,280			78,150			220,879
	Total assets	1,897,218			4,141,072			146,947			137,941			3,208,277			9,531,455
	Capital expenditures	5,671			137,390			13,147			4,776			62,184			223,168
	Nine months ended September 30, 2012
	Revenues	$	1,130,408		$	1,409,776		$	272,359		$	88,549		$	—		$	2,901,092
	Income (loss) from operations	94,163			(388,563		)	34,937			(3,757		)	(186,634		)	(449,854		)
	Depreciation, depletion and amortization	122,298			210,789			29,894			9,704			1,946			374,631
	Amortization of acquired sales contracts, net	(1,374		)	(21,658		)	—			471			—			(22,561		)
	Asset impairment and mine closure costs	—			524,115			—			(437		)	(239		)	523,439
	Total assets	2,234,941			4,130,273			676,057			169,981			2,724,602			9,935,854
	Capital expenditures	15,399			222,177			42,761			8,153			15,478			303,968
	A reconciliation of segment income (loss) from operations to consolidated loss before income taxes follows:
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
		(In thousands)
	Income (loss) from operations	$	(234,753	)	$	119,242		$	(322,463	)	$	(449,854	)
	Interest expense	(95,624		)	(75,710		)	(285,454		)	(229,210		)
	Interest and investment income	697			1,459			4,749			3,568
	Other nonoperating expense	$	—		$	—		$	—		$	(19,042	)
	Income (loss) from continuing operations before income taxes	$	(329,680	)	$	44,991		$	(603,168	)	$	(694,538	)

Supplemental_Condensed_Consoli

Supplemental Condensed Consolidating Financial Information	9 Months Ended
	Sep. 30, 2013
Supplemental Condensed Consolidating Financial Information [Abstract]	'
Supplemental Condensed Consolidating Financial Information Text Block	'
	Supplemental Condensed 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 September 30, 2013
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	791,269		$	—		$	—		$	791,269
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	169			688,543			—			—			688,712
	Depreciation, depletion and amortization	1,549			104,765			9			—			106,323
	Amortization of acquired sales contracts, net	—			(2,568		)	—			—			(2,568		)
	Change in fair value of coal derivatives and coal trading activities, net	—			9,753			—			—			9,753
	Asset impairment and mine closure costs	57,668			142,729			—			—			200,397
	Selling, general and administrative expenses	19,104			8,214			1,482			—			28,800
	Other operating income, net	2,345			(7,740		)	—			—			(5,395		)
		80,835			943,696			1,491			—			1,026,022
	Loss from investment in subsidiaries	(61,537		)	—			—			61,537			—
	Loss from operations	(142,372		)	(152,427		)	(1,491		)	61,537			(234,753		)
	Interest expense, net
	Interest expense	(114,536		)	(6,222		)	(1,070		)	26,204			(95,624		)
	Interest and investment income	6,606			18,975			1,320			(26,204		)	697
		(107,930		)	12,753			250			—			(94,927		)
	Loss from continuing operations before income taxes	(250,302		)	(139,674		)	(1,241		)	61,537			(329,680		)
	Provision for (benefit from) income taxes	(121,939		)	—			26			—			(121,913		)
	Loss from continuing operations	(128,363		)	(139,674		)	(1,267		)	61,537			(207,767		)
	Income from discontinued operations, including gain on sale - net of tax	—			79,404			—			—			79,404
	Net loss	$	(128,363	)	$	(60,270	)	$	(1,267	)	$	61,537		$	(128,363	)
	Total comprehensive loss	$	(125,996	)	$	(59,241	)	$	(1,267	)	$	60,508		$	(125,996	)
	Condensed Consolidating Statements of Operations
	Nine Months Ended September 30, 2013
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	2,294,971		$	—		$	—		$	2,294,971
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	4,881			1,989,772			—			—			1,994,653
	Depreciation, depletion and amortization	4,430			323,144			27			—			327,601
	Amortization of acquired sales contracts, net	—			(7,587		)	—			—			(7,587		)
	Change in fair value of coal derivatives and coal trading activities, net	—			2,053			—			—			2,053
	Asset impairment and mine closure costs	78,150			142,729			—			—			220,879
	Selling, general and administrative expenses	63,006			28,978			4,327			—			96,311
	Other operating income, net	(4,663		)	(10,704		)	(1,109		)	—			(16,476		)
		145,804			2,468,385			3,245			—			2,617,434
	Loss from investment in subsidiaries	(42,199		)	—			—			42,199			—
	Loss from operations	(188,003		)	(173,414		)	(3,245		)	42,199			(322,463		)
	Interest expense, net
	Interest expense	(336,310		)	(18,502		)	(3,170		)	72,528			(285,454		)
	Interest and investment income	22,917			49,986			4,374			(72,528		)	4,749
		(313,393		)	31,484			1,204			—			(280,705		)
	Loss from continuing operations before income taxes	(501,396		)	(141,930		)	(2,041		)	42,199			(603,168		)
	Provision for (benefit from) income taxes	(230,778		)	—			44			—			(230,734		)
	Loss from continuing operations	(270,618		)	(141,930		)	(2,085		)	42,199			(372,434		)
	Income from discontinued operations, including gain on sale - net of tax	—			101,816			—			—			101,816
	Net loss	$	(270,618	)	$	(40,114	)	$	(2,085	)	$	42,199		$	(270,618	)
	Total comprehensive loss	$	(262,717	)	$	(39,175	)	$	(2,085	)	$	41,260		$	(262,717	)
	Condensed Consolidating Statements of Operations
	Three Months Ended September 30, 2012
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
	(In thousands)
Revenues	$	—		$	975,170		$	—		$	—		$	975,170
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)	2,437			806,052			—			—			808,489
Depreciation, depletion and amortization	1,399			117,534			9			—			118,942
Amortization of acquired sales contracts, net	—			(4,093		)	—			—			(4,093		)
Change in fair value of coal derivatives and coal trading activities, net	—			5,840			—			—			5,840
Asset impairment and mine closure costs	—			(2,144		)	—			—			(2,144		)
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Selling, general and administrative expenses	22,051			9,432			1,783			—			33,266
Other operating income, net	(11,052		)	(13,699		)	(89		)	—			(24,840		)
	14,835			839,390			1,703			—			855,928
Income from investment in subsidiaries	164,152			—			—			(164,152		)	—
Income (loss) from operations	149,317			135,780			(1,703		)	(164,152		)	119,242
Interest expense, net
Interest expense	(91,577		)	(6,870		)	(649		)	23,386			(75,710		)
Interest and investment income	8,329			14,570			1,946			(23,386		)	1,459
	(83,248		)	7,700			1,297			—			(74,251		)
Income (loss) from continuing operations before income taxes	66,069			143,480			(406		)	(164,152		)	44,991
Provision for income taxes	20,318			—			—			—			20,318
Income (loss) from continuing operations	45,751			143,480			(406		)	(164,152		)	24,673
Income from discontinued operations, net of tax	—			21,078			—			—			21,078
Net income (loss)	$	45,751		$	164,558		$	(406	)	$	(164,152	)	$	45,751
Total comprehensive income (loss)	$	44,299		$	163,375		$	(406	)	$	(162,969	)	$	44,299
Condensed Consolidating Statements of Operations
Nine Months Ended September 30, 2012
	Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
				Subsidiaries			Guarantor
							Subsidiaries
	(In thousands)
Revenues	$	—		$	2,901,092		$	—		$	—		$	2,901,092
Costs, expenses and other													—
Cost of sales (exclusive of items shown separately below)	7,694			2,406,612			—			—			2,414,306
Depreciation, depletion and amortization	3,959			370,648			24			—			374,631
Amortization of acquired sales contracts, net	—			(22,561		)	—			—			(22,561		)
Change in fair value of coal derivatives and coal trading activities, net	—			(29,827		)	—			—			(29,827		)
Asset impairment and mine closure costs	—			523,439			—			—			523,439
Goodwill impairment	—			115,791			—			—			115,791
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Selling, general and administrative expenses	62,469			30,965			5,871			—			99,305
Other operating income, net	(7,693		)	(23,811		)	(13,102		)	—			(44,606		)
	66,429			3,291,724			(7,207		)	—			3,350,946
Loss from investment in subsidiaries	(324,429		)	—			—			324,429			—
Income (loss) from operations	(390,858		)	(390,632		)	7,207			324,429			(449,854		)
Interest expense, net
Interest expense	(263,381		)	(27,285		)	(2,382		)	63,838			(229,210		)
Interest and investment income	19,087			42,508			5,811			(63,838		)	3,568
	(244,294		)	15,223			3,429			—			(225,642		)
Other non-operating expense
Net loss resulting from early retirement of ICG debt	(17,349		)	(1,693		)	—			—			(19,042		)
Income (loss) from continuing operations before income taxes	(652,501		)	(377,102		)	10,636			324,429			(694,538		)
Provision for (benefit from) income taxes	(264,237		)	—			1,581			—			(262,656		)
Income (loss) from continuing operations	(388,264		)	(377,102		)	9,055			324,429			(431,882		)
Income from discontinued operations, net of tax	—			43,618			—			—			43,618
Net Income (loss)	(388,264		)	(333,484		)	9,055			324,429			(388,264		)
Less: Net income attributable to noncontrolling interest	(268		)	—			—			—			(268		)
Net Income (loss) attributable to Arch Coal, Inc.	$	(388,532	)	$	(333,484	)	$	9,055		$	324,429		$	(388,532	)
Total comprehensive income (loss)	$	(385,523	)	$	(336,648	)	$	9,055		$	327,593		$	(385,523	)
Condensed Consolidating Balance Sheets
September 30, 2013
	Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
				Subsidiaries			Subsidiaries
	(In thousands)
Assets
Cash and cash equivalents	$	1,021,245		$	100,410		$	11,473		$	—		$	1,133,128
Restricted cash	—			—			—			—			—
Short term investments	248,724			—			—			—			248,724
Receivables	7,847			21,178			190,493			(4,679		)	214,839
Inventories	—			287,409			—			—			287,409
Other	96,992			48,270			277			—			145,539
Total current assets	1,374,808			457,267			202,243			(4,679		)	2,029,639
Property, plant and equipment, net	25,526			6,752,687			46			(34		)	6,778,225
Investment in subsidiaries	7,992,601			—			—			(7,992,601		)	—
Intercompany receivables	—			1,986,992			—			(1,986,992		)	—
Note receivable from Arch Western	675,000			—			—			(675,000		)	—
Other	147,950			575,551			90			—			723,591
Total other assets	8,815,551			2,562,543			90			(10,654,593		)	723,591
Total assets	$	10,215,885		$	9,772,497		$	202,379		$	(10,659,306	)	$	9,531,455
Liabilities and Stockholders’ Equity
Accounts payable	$	20,728		$	186,468		$	77		$	—		$	207,273
Accrued expenses and other current liabilities	107,756			246,063			314			(4,679		)	349,454
Current maturities of debt	19,343			3,707			—			—			23,050
Total current liabilities	147,827			436,238			391			(4,679		)	579,777
Long-term debt	5,055,021			19,363			—			—			5,074,384
Intercompany payables	1,810,718			—			176,274			(1,986,992		)	—
Note payable to Arch Coal	—			675,000			—			(675,000		)	—
Asset retirement obligations	1,150			409,971			—			—			411,121
Accrued pension benefits	36,304			32,235			—			—			68,539
Accrued postretirement benefits other than pension	14,267			30,012			—			—			44,279
Accrued workers’ compensation	25,601			56,413			—			—			82,014
Deferred income taxes	484,130			—			—			—			484,130
Other noncurrent liabilities	59,179			146,055			323			—			205,557
Total liabilities	7,634,197			1,805,287			176,988			(2,666,671		)	6,949,801
Stockholders’ equity	2,581,688			7,967,210			25,391			(7,992,635		)	2,581,654
Total liabilities and stockholders’ equity	$	10,215,885		$	9,772,497		$	202,379		$	(10,659,306	)	$	9,531,455
Condensed Consolidating Balance Sheets
December 31, 2012
	Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
				Subsidiaries			Subsidiaries
	(In thousands)
Assets
Cash and cash equivalents	$	671,313		$	100,468		$	12,841		$	—		$	784,622
Restricted cash	3,453			—			—			—			3,453
Short term investments	234,305			—			—			—			234,305
Receivables	49,281			40,452			247,171			(4,824		)	332,080
Inventories	—			365,424			—			—			365,424
Other	106,786			86,877			557			—			194,220
Total current assets	1,065,138			593,221			260,569			(4,824		)	1,914,104
Property, plant and equipment, net	27,476			7,309,550			72			—			7,337,098
Investment in subsidiaries	8,254,508			—			—			(8,254,508		)	—
Intercompany receivables	—			1,600,311			—			(1,600,311		)	—
Note receivable from Arch Western	675,000			—			—			(675,000		)	—
Other	187,171			568,314			90			—			755,575
Total other assets	9,116,679			2,168,625			90			(10,529,819		)	755,575
Total assets	$	10,209,293		$	10,071,396		$	260,731		$	(10,534,643	)	$	10,006,777
Liabilities and Stockholders’ Equity
Accounts payable	$	19,859		$	204,370		$	189		$	—		$	224,418
Accrued expenses and other current liabilities	65,293			259,162			124			(4,824		)	319,755
Current maturities of debt	32,054			842			—			—			32,896
Total current liabilities	117,206			464,374			313			(4,824		)	577,069
Long-term debt	5,061,925			23,954			—			—			5,085,879
Intercompany payables	1,367,739			—			232,572			(1,600,311		)	—
Note payable to Arch Coal	—			675,000			—			(675,000		)	—
Asset retirement obligations	1,646			408,059			—			—			409,705
Accrued pension benefits	33,456			34,174			—			—			67,630
Accrued postretirement benefits other than pension	13,953			31,133			—			—			45,086
Accrued workers’ compensation	25,323			56,306			—			—			81,629
Deferred income taxes	664,182			—			—			—			664,182
Other noncurrent liabilities	69,296			151,360			374			—			221,030
Total liabilities	7,354,726			1,844,360			233,259			(2,280,135		)	7,152,210
Stockholders’ equity	2,854,567			8,227,036			27,472			(8,254,508		)	2,854,567
Total liabilities and stockholders’ equity	$	10,209,293		$	10,071,396		$	260,731		$	(10,534,643	)	$	10,006,777
Condensed Consolidating Statements of Cash Flows
Nine Months Ended September 30, 2013
	Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
				Subsidiaries			Subsidiaries
	(In thousands)
Cash provided by (used in) operating activities	$	(22,206	)	$	153,868		$	54,930		$	—		$	186,592
Investing Activities
Capital expenditures	(2,488		)	(220,680		)	—			—			(223,168		)
Minimum royalty payments	—			(10,901		)	—			—			(10,901		)
Proceeds from dispositions of property, plant and equipment	—			8,799			—			—			8,799
Proceeds from sales-leaseback transactions	—			34,919			—			—			34,919
Proceeds from sale of Canyon Fuel	—			422,663			—			—			422,663
Purchases of short term investments	(85,418		)	—			—			—			(85,418		)
Proceeds from sales of short term investments	67,255			—			—			—			67,255
Investments in and advances to affiliates	(4,016		)	(7,492		)	—			384			(11,124		)
Change in restricted cash	3,453			—			—			—			3,453
Cash provided by (used in) investing activities	(21,214		)	227,308			—			384			206,478
Financing Activities
Contributions from parent	—			384			—			(384		)	—
Payments on term loan	(12,375		)	—			—			—			(12,375		)
Payments to retire debt	—			(384		)	—			—			(384		)
Net payments on other debt	(12,700		)	—			—			—			(12,700		)
Dividends paid	(19,105		)	—			—			—			(19,105		)
Transactions with affiliates, net	437,532			(381,234		)	(56,298		)	—			—
Cash provided by (used in) financing activities	393,352			(381,234		)	(56,298		)	(384		)	(44,564		)
Increase (decrease) in cash and cash equivalents	349,932			(58		)	(1,368		)	—			348,506
Cash and cash equivalents, beginning of period	671,313			100,468			12,841			—			784,622
Cash and cash equivalents, end of period	$	1,021,245		$	100,410		$	11,473		$	—		$	1,133,128
Condensed Consolidating Statements of Cash Flows
Nine Months Ended September 30, 2012
	Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
				Subsidiaries			Subsidiaries
	(In thousands)
Cash provided by (used in) operating activities	$	(610,129	)	$	874,545		$	91,979		$	—		$	356,395
Investing Activities
Capital expenditures	(4,150		)	(299,818		)	—			—			(303,968		)
Minimum royalty payments	—			(9,192		)	—			—			(9,192		)
Proceeds from dispositions of property, plant and equipment	—			1,127			21,497			—			22,624
Purchases of short term investments	(99,628		)	—			—			—			(99,628		)
Investments in and advances to affiliates	(5,138		)	(9,082		)	—			1,535			(12,685		)
Purchase of noncontrolling interest	—			(17,500		)	—			—			(17,500		)
Change in restricted cash	6,872			—			—			—			6,872
Cash provided by (used in) investing activities	(102,044		)	(334,465		)	21,497			1,535			(413,477		)
Financing Activities
Contributions from parent	—			1,535			—			(1,535		)	—
Proceeds from issuance of term loan	1,386,000			—			—			—			1,386,000
Payments on term loan	(3,500		)	—			—			—			(3,500		)
Payments to retire debt	—			(452,806		)	—			—			(452,806		)
Net decrease in borrowings under lines of credit	(375,000		)	—			(6,300		)	—			(381,300		)
Net payments from other debt	(13,078		)	—			—			—			(13,078		)
Debt financing costs	(34,640		)	—			(46		)	—			(34,686		)
Dividends paid	(36,072		)	—			—			—			(36,072		)
Proceeds from exercise of options under incentive plans	5,131			—			—			—			5,131
Transactions with affiliates, net	30,338			66,364			(96,702		)	—			—
Cash provided by (used in) financing activities	959,179			(384,907		)	(103,048		)	(1,535		)	469,689
Increase in cash and cash equivalents	247,006			155,173			10,428			—			412,607
Cash and cash equivalents, beginning of period	66,542			70,258			1,349			—			138,149
Cash and cash equivalents, end of period	$	313,548		$	225,431		$	11,777		$	—		$	550,756

Basis_of_Presentation_Policy

Basis of Presentation (Policy)	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
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. In addition, the Company is developing a metallurgical coal mine in West Virginia. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation.
	The Company completed the sale of a subsidiary comprised of three mining complexes in the Western Bituminous reportable segment ("WBIT") on August 16, 2013. The results of these mining complexes have been segregated from continuing operations and are reflected, net of tax, as discontinued operations in the condensed consolidated statements of operations for all periods presented. See further discussion in Note 3, "Discontinued Operations".
	In response to decreasing demand for thermal coal in Appalachia, the Company closed four mining complexes, temporarily idled a fifth complex, and curtailed production at other mines in the region in the second quarter of 2012. The operations continued to ship from inventory into the third quarter of 2012. The results for the closed and idled complexes are reflected in continuing operations in the condensed consolidating statements of operations for the three and nine month periods ended September 30, 2012. See further discussion in Note 5, "Impairment Charges".
	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 and nine month periods ended September 30, 2013 are not necessarily indicative of results to be expected for the year ending December 31, 2013. 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, 2012 included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
ResultsOfDiscontinuedOperationsTableTextBlock [Table Text Block]	'
	The following table summarizes the results of discontinued operations:
		Three Months Ended September 30,					Nine Months Ended September 30,
		2013		2012			2013		2012
		(In thousands)
	Total Revenues	$	45,763	$	112,448		$	219,002	$	289,715
	Income from discontinued operations before income taxes	$	3,429	$	16,718		$	32,166	$	50,911
	Gain on sale	115,679		—			115,679		—
	Income tax expense (benefit)	39,704		(4,360		)	46,029		7,293
	Income from discontinued operations, including gain on sale - net of tax	$	79,404	$	21,078		$	101,816	$	43,618
	Basic earnings per common share from discontinued operations	$	0.37	$	0.1		$	0.48	$	0.21
	Diluted earnings per common share from discontinued operations	$	0.37	$	0.1		$	0.48	$	0.21

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	'
	ollowing items are included in accumulated other comprehensive loss:
						Pension,
						Postretirement
						and Other							Accumulated
						Post-							Other
		Derivative				Employment				Available-for-			Comprehensive
		Instruments				Benefits				Sale Securities			Loss
		(In thousands)
	Balance at December 31, 2012	$	2,244			$	(18,286	)		$	(465	)	$	(16,507	)
	Unrealized gains	1,197				1,938				4,653			7,788
	Amounts reclassified from accumulated other comprehensive income	(1,339		)		1,252				200			113
	Balance at September 30, 2013	$	2,102			$	(15,096	)		$	4,388		$	(8,606	)
Schedule of comprehensive income reclassifications [Table Text Block]	'
	The following amounts were reclassified out of accumulated other comprehensive loss:
			Amount Reclassified from
			Accumulated Comprehensive Loss								Line Item in the
	Details about accumulated other		Three Months Ended				Nine Months Ended				Condensed Consolidated
	comprehensive income components		30-Sep-13				30-Sep-13				Statement of Operations
			(In thousands)
	Derivative instruments		$	692			$	2,093			Revenues
			(249		)		(754		)		Provision for (benefit from) income taxes
			$	443			$	1,339			Net of tax
	Pension, postretirement and other post-employment benefits
	Amortization of prior service credits		$	5,573			$	11,154		1
	Amortization of actuarial gains (losses), net		(3,823		)		(13,108		)	1
			1,750				(1,954		)		Total before tax
			(631		)		702				Provision for (benefit from) income taxes
			$	1,119			$	(1,252	)		Net of tax
	Available-for-sale securities		$	(4	)		$	(313	)	2	Interest and investment income
			2				113				Provision for (benefit from) income taxes
			$	(2	)		$	(200	)		Net of tax
	1 Production-related benefits and workers' compensation costs are included in costs to produce coal. See Note 14, "Workers' Compensation Expense" and Note 15 "Employee Benefit Plans" for more information about pension, postretirement and postemployment benefit costs.
	2 The gains and losses on sales of available-for-sale-securities are determined on a specific identification basis.

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories consist of the following:
		30-Sep		31-Dec
		2013		2012
		(In thousands)
	Coal	$	134,481	$	180,917
	Repair parts and supplies	143,763		172,139
	Work-in-process	9,165		12,368
		$	287,409	$	365,424

Investments_in_AvailableforSal1

Investments in Available-for-Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2013
Available-for-sale Securities [Abstract]	'
Available-for-sale Securities [Table Text Block]	'
	The Company's investments in available-for-sale marketable securities are as follows:
		September 30, 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	$	123,809	$	7	$	(126	)	$	123,690	$	123,690	$	—
	Corporate notes and bonds	125,479		21		(466		)	125,034		125,034		—
	Equity securities	5,271		10,284		(2,865		)	12,690		—		12,690
	Total Investments	$	254,559	$	10,312	$	(3,457	)	$	261,414	$	248,724	$	12,690
		December 31, 2012
											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	$	146,993	$	2	$	(412	)	$	146,583	$	146,583	$	—
	Corporate notes and bonds	88,118		—		(396		)	87,722		87,722		—
	Equity securities	5,271		2,704		(2,628		)	5,347		—		5,347
	Total Investments	$	240,382	$	2,706	$	(3,436	)	$	239,652	$	234,305	$	5,347

Equity_Investments_And_Members1

Equity Investments And Membership Interests In Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2013
Equity Method Investments and Joint Ventures [Abstract]	'
Schedule Of Equity Method Investments	'
	In thousands	Knight Hawk			DKRW			DTA			Tenaska			Millennium			Tongue River			Total
	Balance at December 31, 2012	$	149,063		$	15,515		$	15,462		$	15,264		$	32,214		$	14,697		$	242,215
	Advances to (distributions from) affiliates, net	(5,342		)	—			2,537			—			4,954			2,696			4,845
	Equity in comprehensive income (loss)	13,362			(1,832		)	(3,855		)	—			(1,953		)	(281		)	5,441
	Impairment of equity investment	—			(13,683		)	—			(15,264		)	—			—			(28,947		)
	Balance at September 30, 2013	$	157,083		$	—		$	14,144		$	—		$	35,215		$	17,112		$	223,554

Derivatives_Tables

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Price Risk Derivatives	'
	At September 30, 2013, the Company held derivatives for risk management purposes that are expected to settle in the following years:
	(Tons in thousands)		2013			2014			2015			Total
	Coal sales		2,314			4,458			780			7,552
	Coal purchases		609			1,260			—			1,869
Disclosure Of Fair Value Of Derivatives	'
			30-Sep-13											31-Dec-12
	Fair Value of Derivatives		Asset				Liability							Asset			Liability
	(In thousands)		Derivative				Derivative							Derivative			Derivative
	Derivatives Designated as Hedging Instruments
	Coal		$	3,009			$	(4	)					$	3,277		$	(10	)
	Derivatives Not Designated as Hedging Instruments
	Heating oil -- diesel purchases		3,825				—							7,379			—
	Heating oil -- fuel surcharges		400				—							1,961			—
	Coal -- held for trading purposes		59,789				(52,383		)					17,403			(16,933		)
	Coal -- risk management		15,907				(3,903		)					24,843			(7,342		)
	Total		79,921				(56,286		)					51,586			(24,275		)
	Total derivatives		82,930				(56,290		)					54,863			(24,285		)
	Effect of counterparty netting		(55,869		)		55,869							(22,548		)	22,548
	Net derivatives as classified in the balance sheets		$	27,061			$	(421	)		$	26,640		$	32,315		$	(1,737	)	$	30,578
					30-Sep-13				31-Dec-12
	Net derivatives as reflected on the balance sheets
	Heating oil		Other current assets		$	4,225			$	9,340
	Coal		Coal derivative assets		22,836				22,975
			Coal derivative liabilities		(421		)		(1,737		)
					$	26,640			$	30,578
Effects Of Derivatives On Measures Of Financial Performance	'
	Derivatives used in Cash Flow Hedging Relationships (in thousands)
	For the nine months ended September 30
			Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)								Gains (Losses) Reclassified from Other Comprehensive Income into Income
											(Effective Portion)
			2013				2012				2013			2012
	Coal sales	(1)	$	2,308			$	4,983			$	2,822		$	1,552
	Coal purchases	(2)	(511		)		(1,122		)		(633		)	—
	Totals		$	1,797			$	3,861			$	2,189		$	1,552
	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 nine month periods ended September 30, 2013 and 2012.
	Derivatives Not Designated as Hedging Instruments (in thousands)
	For the nine months ended September 30
			Gain (Loss) Recognized
			2013				2012
	Coal — unrealized	(3)	$	(5,089	)		$	23,670
	Coal — realized	(4)	$	25,725			$	25,901
	Heating oil — diesel purchases	(4)	$	(9,760	)		$	(16,902	)
	Heating oil — fuel surcharges	(4)	$	(817	)		$	(1,140	)
	____________________________________________________________
	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
	Derivatives used in Cash Flow Hedging Relationships (in thousands)
	For the three months ended September 30,
			Gain (Loss) Recognized in Other Comprehensive Income(Effective Portion)								Gains (Losses) Reclassified from Other Comprehensive Income into Income
											(Effective Portion)
			2013				2012				2013			2012
	Coal sales	(1)	$	3,132			$	259			$	911		$	542
	Coal purchases	(2)	(942		)		(178		)		(123		)	—
	Totals		$	2,190			$	81			$	788		$	542
	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 September 30, 2013 and 2012.
	Derivatives Not Designated as Hedging Instruments (in thousands)
	For the three months ended September 30,
			Gain (Loss) Recognized
			2013				2012
	Coal — unrealized	(3)	$	(10,668	)		$	(11,328	)
	Coal — realized	(4)	$	9,929			$	14,072
	Heating oil — diesel purchases	(4)	$	(288	)		$	5,184
	Heating oil — fuel surcharges	(4)	$	(222	)		$	1,092
	____________________________________________________________
	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

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Debt	'
		September 30,		December 31,
		2013		2012
		(In thousands)
	Term loan ($1.63 billion face value) due 2018	$	1,617,097	$	1,627,384
	8.75% senior notes ($600.0 million face value) due 2016	592,646		590,999
	7.00% senior notes due 2019 at par	1,000,000		1,000,000
	9.875% senior notes ($375.0 million face value) due 2019	361,779		360,042
	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	25,912		40,350
		5,097,434		5,118,775
	Less current maturities of debt	23,050		32,896
	Long-term debt	$	5,074,384	$	5,085,879

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
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:
		Fair Value at September 30, 2013
		Total			Level 1			Level 2		Level 3
		(In thousands)
	Assets:
	Investments in marketable securities	$	261,414		$	101,338		$	160,076	$	—
	Derivatives	27,061			22,750			—		4,311
	Total assets	$	288,475		$	124,088		$	160,076	$	4,311
	Liabilities:
	Derivatives	$	421		$	—		$	204	$	217
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 September 30, 2013			Nine Months Ended September 30, 2013
		(In thousands)
	Balance, beginning of period	$	3,438		$	8,174
	Realized and unrealized losses recognized in earnings, net	(570		)	(9,882		)
	Purchases	1,464			7,317
	Issuances	—			(25		)
	Settlements	(238		)	(1,490		)
	Ending balance	$	4,094		$	4,094

Accrued_Expenses_and_Other_Cur1

Accrued Expenses and Other Current Liabilities Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2013
Accrued Expenses and Other Current Liabilities [Abstract]	'
Schedule of Accrued Liabilities [Table Text Block]	'
	Accrued expenses and other current liabilities consist of the following:
		September 30,		December 31,
		2013		2012
		(In thousands)
	Payroll and employee benefits	$	68,245	$	72,405
	Taxes other than income taxes	113,872		121,029
	Interest	80,454		42,413
	Acquired sales contracts	14,461		14,038
	Workers’ compensation	12,215		10,371
	Asset retirement obligations	38,895		38,920
	Other	20,891		18,842
		$	349,033	$	318,018

Workers_Compensation_Expense_T

Workers' Compensation Expense (Tables)	9 Months Ended
	Sep. 30, 2013
Workers' Compensation Expense [Abstract]	'
Workers' Compensation Expense	'
		Three Months Ended September 30,				Nine Months Ended September 30,
		2013		2012		2013		2012
		(In thousands)
	Service cost	$	363	$	419	$	1,373	$	1,458
	Interest cost	709		629		2,022		1,708
	Net amortization	262		—		731		(574		)
	Curtailments	816		—		816		1,933
	Total occupational disease	2,150		1,048		4,942		4,525
	Traumatic injury claims and assessments	4,114		7,453		16,263		19,052
	Total workers’ compensation expense	$	6,264	$	8,501	$	21,205	$	23,577

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2013
Pension and Other Postretirement Benefit Expense [Abstract]	'
Other Postretirement Benefit Costs Table Text Block [Table Text Block]	'
	The following table details the components of other postretirement benefit costs (credits):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
		(In thousands)
	Service cost	$	497		$	541		$	1,591		$	1,629
	Interest cost	427			508			1,273			1,519
	Curtailments	(5,444		)	(2,212		)	(5,444		)	(4,049		)
	Amortization of prior service credits	(2,641		)	(2,837		)	(8,121		)	(8,708		)
	Amortization of other actuarial losses (gains)	(55		)	(130		)	(53		)	(391		)
	Net benefit credit	$	(7,216	)	$	(4,130	)	$	(10,754	)	$	(10,000	)
Pension Benefit Costs	'
		Three Months Ended September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
		(In thousands)
	Service cost	$	6,672		$	6,156		$	21,162		$	21,062
	Interest cost	3,994			3,683			11,796			11,755
	Curtailments	47			—			47			324
	Expected return on plan assets	(5,848		)	(5,508		)	(17,690		)	(16,523		)
	Amortization of prior service costs (credits)	(51		)	273			(152		)	200
	Amortization of other actuarial losses	3,617			3,248			12,430			11,019
	Net benefit cost	$	8,431		$	7,852		$	27,593		$	27,837

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Schedule Of Operating Segment Results	'
		PRB			APP			WBIT			Other			Corporate,			Consolidated
											Operating			Other and
											Segments			Eliminations
		(in thousands)
	Three months ended September 30, 2013
	Revenues	$	420,521		$	263,188		$	78,022		$	29,538		$	—		$	791,269
	Income (loss) from operations	20,694			(157,883		)	9,287			(9,231		)	(97,620		)	(234,753		)
	Depreciation, depletion and amortization	46,619			46,529			9,436			2,523			1,216			106,323
	Amortization of acquired sales contracts, net	(864		)	(2,691		)	—			987			—			(2,568		)
	Asset impairment and mine closure costs	—			126,449			—			16,280			57,668			200,397
	Capital expenditures	1,695			44,624			5,859			1,263			663			54,104
	Three months ended September 30, 2012
	Revenues	$	406,719		$	436,409		$	105,515		$	26,527		$	—		$	975,170
	Income (loss) from operations	38,873			88,695			24,110			(1,298		)	(31,138		)	119,242
	Depreciation, depletion and amortization	43,944			61,596			9,985			2,594			823			118,942
	Amortization of acquired sales contracts, net	(589		)	(3,711		)	—			207			—			(4,093		)
	Asset impairment and mine closure costs	—			(1,801		)	—			(210		)	(133		)	(2,144		)
	Capital expenditures	5,620			77,772			13,510			3,640			1,353			101,895
	Nine months ended September 30, 2013
	Revenues	$	1,135,892		$	883,484		$	187,374		$	88,221		$	—		$	2,294,971
	Income (loss) from operations	53,244			(190,278		)	23,766			(407		)	(208,788		)	(322,463		)
	Depreciation, depletion and amortization	130,993			157,866			26,528			7,792			4,422			327,601
	Amortization of acquired sales contracts, net	(3,004		)	(7,975		)	—			3,392			—			(7,587		)
	Asset impairment and mine closure costs	—			126,449			—			16,280			78,150			220,879
	Total assets	1,897,218			4,141,072			146,947			137,941			3,208,277			9,531,455
	Capital expenditures	5,671			137,390			13,147			4,776			62,184			223,168
	Nine months ended September 30, 2012
	Revenues	$	1,130,408		$	1,409,776		$	272,359		$	88,549		$	—		$	2,901,092
	Income (loss) from operations	94,163			(388,563		)	34,937			(3,757		)	(186,634		)	(449,854		)
	Depreciation, depletion and amortization	122,298			210,789			29,894			9,704			1,946			374,631
	Amortization of acquired sales contracts, net	(1,374		)	(21,658		)	—			471			—			(22,561		)
	Asset impairment and mine closure costs	—			524,115			—			(437		)	(239		)	523,439
	Total assets	2,234,941			4,130,273			676,057			169,981			2,724,602			9,935,854
	Capital expenditures	15,399			222,177			42,761			8,153			15,478			303,968
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 September 30,						Nine Months Ended September 30,
		2013			2012			2013			2012
		(In thousands)
	Income (loss) from operations	$	(234,753	)	$	119,242		$	(322,463	)	$	(449,854	)
	Interest expense	(95,624		)	(75,710		)	(285,454		)	(229,210		)
	Interest and investment income	697			1,459			4,749			3,568
	Other nonoperating expense	$	—		$	—		$	—		$	(19,042	)
	Income (loss) from continuing operations before income taxes	$	(329,680	)	$	44,991		$	(603,168	)	$	(694,538	)

Supplemental_Condensed_Consoli1

Supplemental Condensed Consolidating Financial Information (Tables)	9 Months Ended
	Sep. 30, 2013
Supplemental Condensed Consolidating Financial Information [Abstract]	'
Schedule of Condensed Consolidating Statements of Income [Table Text Block]	'
	Condensed Consolidating Statements of Operations
	Three Months Ended September 30, 2013
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	791,269		$	—		$	—		$	791,269
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	169			688,543			—			—			688,712
	Depreciation, depletion and amortization	1,549			104,765			9			—			106,323
	Amortization of acquired sales contracts, net	—			(2,568		)	—			—			(2,568		)
	Change in fair value of coal derivatives and coal trading activities, net	—			9,753			—			—			9,753
	Asset impairment and mine closure costs	57,668			142,729			—			—			200,397
	Selling, general and administrative expenses	19,104			8,214			1,482			—			28,800
	Other operating income, net	2,345			(7,740		)	—			—			(5,395		)
		80,835			943,696			1,491			—			1,026,022
	Loss from investment in subsidiaries	(61,537		)	—			—			61,537			—
	Loss from operations	(142,372		)	(152,427		)	(1,491		)	61,537			(234,753		)
	Interest expense, net
	Interest expense	(114,536		)	(6,222		)	(1,070		)	26,204			(95,624		)
	Interest and investment income	6,606			18,975			1,320			(26,204		)	697
		(107,930		)	12,753			250			—			(94,927		)
	Loss from continuing operations before income taxes	(250,302		)	(139,674		)	(1,241		)	61,537			(329,680		)
	Provision for (benefit from) income taxes	(121,939		)	—			26			—			(121,913		)
	Loss from continuing operations	(128,363		)	(139,674		)	(1,267		)	61,537			(207,767		)
	Income from discontinued operations, including gain on sale - net of tax	—			79,404			—			—			79,404
	Net loss	$	(128,363	)	$	(60,270	)	$	(1,267	)	$	61,537		$	(128,363	)
	Total comprehensive loss	$	(125,996	)	$	(59,241	)	$	(1,267	)	$	60,508		$	(125,996	)
	Condensed Consolidating Statements of Operations
	Nine Months Ended September 30, 2013
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	2,294,971		$	—		$	—		$	2,294,971
	Costs, expenses and other
	Cost of sales (exclusive of items shown separately below)	4,881			1,989,772			—			—			1,994,653
	Depreciation, depletion and amortization	4,430			323,144			27			—			327,601
	Amortization of acquired sales contracts, net	—			(7,587		)	—			—			(7,587		)
	Change in fair value of coal derivatives and coal trading activities, net	—			2,053			—			—			2,053
	Asset impairment and mine closure costs	78,150			142,729			—			—			220,879
	Selling, general and administrative expenses	63,006			28,978			4,327			—			96,311
	Other operating income, net	(4,663		)	(10,704		)	(1,109		)	—			(16,476		)
		145,804			2,468,385			3,245			—			2,617,434
	Loss from investment in subsidiaries	(42,199		)	—			—			42,199			—
	Loss from operations	(188,003		)	(173,414		)	(3,245		)	42,199			(322,463		)
	Interest expense, net
	Interest expense	(336,310		)	(18,502		)	(3,170		)	72,528			(285,454		)
	Interest and investment income	22,917			49,986			4,374			(72,528		)	4,749
		(313,393		)	31,484			1,204			—			(280,705		)
	Loss from continuing operations before income taxes	(501,396		)	(141,930		)	(2,041		)	42,199			(603,168		)
	Provision for (benefit from) income taxes	(230,778		)	—			44			—			(230,734		)
	Loss from continuing operations	(270,618		)	(141,930		)	(2,085		)	42,199			(372,434		)
	Income from discontinued operations, including gain on sale - net of tax	—			101,816			—			—			101,816
	Net loss	$	(270,618	)	$	(40,114	)	$	(2,085	)	$	42,199		$	(270,618	)
	Total comprehensive loss	$	(262,717	)	$	(39,175	)	$	(2,085	)	$	41,260		$	(262,717	)
	Condensed Consolidating Statements of Operations
	Three Months Ended September 30, 2012
		Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
		(In thousands)
	Revenues	$	—		$	975,170		$	—		$	—		$	975,170
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)	2,437			806,052			—			—			808,489
Depreciation, depletion and amortization	1,399			117,534			9			—			118,942
Amortization of acquired sales contracts, net	—			(4,093		)	—			—			(4,093		)
Change in fair value of coal derivatives and coal trading activities, net	—			5,840			—			—			5,840
Asset impairment and mine closure costs	—			(2,144		)	—			—			(2,144		)
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Selling, general and administrative expenses	22,051			9,432			1,783			—			33,266
Other operating income, net	(11,052		)	(13,699		)	(89		)	—			(24,840		)
	14,835			839,390			1,703			—			855,928
Income from investment in subsidiaries	164,152			—			—			(164,152		)	—
Income (loss) from operations	149,317			135,780			(1,703		)	(164,152		)	119,242
Interest expense, net
Interest expense	(91,577		)	(6,870		)	(649		)	23,386			(75,710		)
Interest and investment income	8,329			14,570			1,946			(23,386		)	1,459
	(83,248		)	7,700			1,297			—			(74,251		)
Income (loss) from continuing operations before income taxes	66,069			143,480			(406		)	(164,152		)	44,991
Provision for income taxes	20,318			—			—			—			20,318
Income (loss) from continuing operations	45,751			143,480			(406		)	(164,152		)	24,673
Income from discontinued operations, net of tax	—			21,078			—			—			21,078
Net income (loss)	$	45,751		$	164,558		$	(406	)	$	(164,152	)	$	45,751
Total comprehensive income (loss)	$	44,299		$	163,375		$	(406	)	$	(162,969	)	$	44,299
Condensed Consolidating Statements of Operations
Nine Months Ended September 30, 2012
	Parent/Issuer			Guarantor			Non-			Eliminations			Consolidated
				Subsidiaries			Guarantor
							Subsidiaries
	(In thousands)
Revenues	$	—		$	2,901,092		$	—		$	—		$	2,901,092
Costs, expenses and other													—
Cost of sales (exclusive of items shown separately below)	7,694			2,406,612			—			—			2,414,306
Depreciation, depletion and amortization	3,959			370,648			24			—			374,631
Amortization of acquired sales contracts, net	—			(22,561		)	—			—			(22,561		)
Change in fair value of coal derivatives and coal trading activities, net	—			(29,827		)	—			—			(29,827		)
Asset impairment and mine closure costs	—			523,439			—			—			523,439
Goodwill impairment	—			115,791			—			—			115,791
Legal contingencies	—			(79,532		)	—			—			(79,532		)
Selling, general and administrative expenses	62,469			30,965			5,871			—			99,305
Other operating income, net	(7,693		)	(23,811		)	(13,102		)	—			(44,606		)
	66,429			3,291,724			(7,207		)	—			3,350,946
Loss from investment in subsidiaries	(324,429		)	—			—			324,429			—
Income (loss) from operations	(390,858		)	(390,632		)	7,207			324,429			(449,854		)
Interest expense, net
Interest expense	(263,381		)	(27,285		)	(2,382		)	63,838			(229,210		)
Interest and investment income	19,087			42,508			5,811			(63,838		)	3,568
	(244,294		)	15,223			3,429			—			(225,642		)
Other non-operating expense
Net loss resulting from early retirement of ICG debt	(17,349		)	(1,693		)	—			—			(19,042		)
Income (loss) from continuing operations before income taxes	(652,501		)	(377,102		)	10,636			324,429			(694,538		)
Provision for (benefit from) income taxes	(264,237		)	—			1,581			—			(262,656		)
Income (loss) from continuing operations	(388,264		)	(377,102		)	9,055			324,429			(431,882		)
Income from discontinued operations, net of tax	—			43,618			—			—			43,618
Net Income (loss)	(388,264		)	(333,484		)	9,055			324,429			(388,264		)
Less: Net income attributable to noncontrolling interest	(268		)	—			—			—			(268		)
Net Income (loss) attributable to Arch Coal, Inc.	$	(388,532	)	$	(333,484	)	$	9,055		$	324,429		$	(388,532	)
Total comprehensive income (loss)	$	(385,523	)	$	(336,648	)	$	9,055		$	327,593		$	(385,523	)
Schedule of Condensed Consolidating Balance Sheets [Table Text Block]	'
	Condensed Consolidating Balance Sheets
	September 30, 2013
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Assets
	Cash and cash equivalents	$	1,021,245		$	100,410		$	11,473		$	—		$	1,133,128
	Restricted cash	—			—			—			—			—
	Short term investments	248,724			—			—			—			248,724
	Receivables	7,847			21,178			190,493			(4,679		)	214,839
	Inventories	—			287,409			—			—			287,409
	Other	96,992			48,270			277			—			145,539
	Total current assets	1,374,808			457,267			202,243			(4,679		)	2,029,639
	Property, plant and equipment, net	25,526			6,752,687			46			(34		)	6,778,225
	Investment in subsidiaries	7,992,601			—			—			(7,992,601		)	—
	Intercompany receivables	—			1,986,992			—			(1,986,992		)	—
	Note receivable from Arch Western	675,000			—			—			(675,000		)	—
	Other	147,950			575,551			90			—			723,591
	Total other assets	8,815,551			2,562,543			90			(10,654,593		)	723,591
	Total assets	$	10,215,885		$	9,772,497		$	202,379		$	(10,659,306	)	$	9,531,455
	Liabilities and Stockholders’ Equity
	Accounts payable	$	20,728		$	186,468		$	77		$	—		$	207,273
	Accrued expenses and other current liabilities	107,756			246,063			314			(4,679		)	349,454
	Current maturities of debt	19,343			3,707			—			—			23,050
	Total current liabilities	147,827			436,238			391			(4,679		)	579,777
	Long-term debt	5,055,021			19,363			—			—			5,074,384
	Intercompany payables	1,810,718			—			176,274			(1,986,992		)	—
	Note payable to Arch Coal	—			675,000			—			(675,000		)	—
	Asset retirement obligations	1,150			409,971			—			—			411,121
	Accrued pension benefits	36,304			32,235			—			—			68,539
	Accrued postretirement benefits other than pension	14,267			30,012			—			—			44,279
	Accrued workers’ compensation	25,601			56,413			—			—			82,014
	Deferred income taxes	484,130			—			—			—			484,130
	Other noncurrent liabilities	59,179			146,055			323			—			205,557
	Total liabilities	7,634,197			1,805,287			176,988			(2,666,671		)	6,949,801
	Stockholders’ equity	2,581,688			7,967,210			25,391			(7,992,635		)	2,581,654
	Total liabilities and stockholders’ equity	$	10,215,885		$	9,772,497		$	202,379		$	(10,659,306	)	$	9,531,455
	Condensed Consolidating Balance Sheets
	December 31, 2012
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Assets
	Cash and cash equivalents	$	671,313		$	100,468		$	12,841		$	—		$	784,622
	Restricted cash	3,453			—			—			—			3,453
	Short term investments	234,305			—			—			—			234,305
	Receivables	49,281			40,452			247,171			(4,824		)	332,080
	Inventories	—			365,424			—			—			365,424
	Other	106,786			86,877			557			—			194,220
	Total current assets	1,065,138			593,221			260,569			(4,824		)	1,914,104
	Property, plant and equipment, net	27,476			7,309,550			72			—			7,337,098
	Investment in subsidiaries	8,254,508			—			—			(8,254,508		)	—
	Intercompany receivables	—			1,600,311			—			(1,600,311		)	—
	Note receivable from Arch Western	675,000			—			—			(675,000		)	—
	Other	187,171			568,314			90			—			755,575
	Total other assets	9,116,679			2,168,625			90			(10,529,819		)	755,575
	Total assets	$	10,209,293		$	10,071,396		$	260,731		$	(10,534,643	)	$	10,006,777
	Liabilities and Stockholders’ Equity
	Accounts payable	$	19,859		$	204,370		$	189		$	—		$	224,418
	Accrued expenses and other current liabilities	65,293			259,162			124			(4,824		)	319,755
	Current maturities of debt	32,054			842			—			—			32,896
	Total current liabilities	117,206			464,374			313			(4,824		)	577,069
	Long-term debt	5,061,925			23,954			—			—			5,085,879
Intercompany payables	1,367,739			—			232,572			(1,600,311		)	—
Note payable to Arch Coal	—			675,000			—			(675,000		)	—
Asset retirement obligations	1,646			408,059			—			—			409,705
Accrued pension benefits	33,456			34,174			—			—			67,630
Accrued postretirement benefits other than pension	13,953			31,133			—			—			45,086
Accrued workers’ compensation	25,323			56,306			—			—			81,629
Deferred income taxes	664,182			—			—			—			664,182
Other noncurrent liabilities	69,296			151,360			374			—			221,030
Total liabilities	7,354,726			1,844,360			233,259			(2,280,135		)	7,152,210
Stockholders’ equity	2,854,567			8,227,036			27,472			(8,254,508		)	2,854,567
Total liabilities and stockholders’ equity	$	10,209,293		$	10,071,396		$	260,731		$	(10,534,643	)	$	10,006,777
Schedule of Condensed Consolidating Statements of Cash Flows [Table Text Block]	'
	Condensed Consolidating Statements of Cash Flows
	Nine Months Ended September 30, 2013
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Cash provided by (used in) operating activities	$	(22,206	)	$	153,868		$	54,930		$	—		$	186,592
	Investing Activities
	Capital expenditures	(2,488		)	(220,680		)	—			—			(223,168		)
	Minimum royalty payments	—			(10,901		)	—			—			(10,901		)
	Proceeds from dispositions of property, plant and equipment	—			8,799			—			—			8,799
	Proceeds from sales-leaseback transactions	—			34,919			—			—			34,919
	Proceeds from sale of Canyon Fuel	—			422,663			—			—			422,663
	Purchases of short term investments	(85,418		)	—			—			—			(85,418		)
	Proceeds from sales of short term investments	67,255			—			—			—			67,255
	Investments in and advances to affiliates	(4,016		)	(7,492		)	—			384			(11,124		)
	Change in restricted cash	3,453			—			—			—			3,453
	Cash provided by (used in) investing activities	(21,214		)	227,308			—			384			206,478
	Financing Activities
	Contributions from parent	—			384			—			(384		)	—
	Payments on term loan	(12,375		)	—			—			—			(12,375		)
	Payments to retire debt	—			(384		)	—			—			(384		)
	Net payments on other debt	(12,700		)	—			—			—			(12,700		)
	Dividends paid	(19,105		)	—			—			—			(19,105		)
	Transactions with affiliates, net	437,532			(381,234		)	(56,298		)	—			—
	Cash provided by (used in) financing activities	393,352			(381,234		)	(56,298		)	(384		)	(44,564		)
	Increase (decrease) in cash and cash equivalents	349,932			(58		)	(1,368		)	—			348,506
	Cash and cash equivalents, beginning of period	671,313			100,468			12,841			—			784,622
	Cash and cash equivalents, end of period	$	1,021,245		$	100,410		$	11,473		$	—		$	1,133,128
	Condensed Consolidating Statements of Cash Flows
	Nine Months Ended September 30, 2012
		Parent/Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
					Subsidiaries			Subsidiaries
		(In thousands)
	Cash provided by (used in) operating activities	$	(610,129	)	$	874,545		$	91,979		$	—		$	356,395
	Investing Activities
	Capital expenditures	(4,150		)	(299,818		)	—			—			(303,968		)
	Minimum royalty payments	—			(9,192		)	—			—			(9,192		)
	Proceeds from dispositions of property, plant and equipment	—			1,127			21,497			—			22,624
	Purchases of short term investments	(99,628		)	—			—			—			(99,628		)
	Investments in and advances to affiliates	(5,138		)	(9,082		)	—			1,535			(12,685		)
	Purchase of noncontrolling interest	—			(17,500		)	—			—			(17,500		)
	Change in restricted cash	6,872			—			—			—			6,872
	Cash provided by (used in) investing activities	(102,044		)	(334,465		)	21,497			1,535			(413,477		)
	Financing Activities
	Contributions from parent	—			1,535			—			(1,535		)	—
	Proceeds from issuance of term loan	1,386,000			—			—			—			1,386,000
	Payments on term loan	(3,500		)	—			—			—			(3,500		)
	Payments to retire debt	—			(452,806		)	—			—			(452,806		)
	Net decrease in borrowings under lines of credit	(375,000		)	—			(6,300		)	—			(381,300		)
	Net payments from other debt	(13,078		)	—			—			—			(13,078		)
	Debt financing costs	(34,640		)	—			(46		)	—			(34,686		)
	Dividends paid	(36,072		)	—			—			—			(36,072		)
	Proceeds from exercise of options under incentive plans	5,131			—			—			—			5,131
	Transactions with affiliates, net	30,338			66,364			(96,702		)	—			—
	Cash provided by (used in) financing activities	959,179			(384,907		)	(103,048		)	(1,535		)	469,689
	Increase in cash and cash equivalents	247,006			155,173			10,428			—			412,607
	Cash and cash equivalents, beginning of period	66,542			70,258			1,349			—			138,149
	Cash and cash equivalents, end of period	$	313,548		$	225,431		$	11,777		$	—		$	550,756

Basis_of_Presentation_Narrativ

Basis of Presentation (Narrative) (Details)	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
number of mining complexes temporarily idled	1
Discontinued Operations [Member]	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'
Number of mining complexes operated	3
Long-Lived Assets to be Abandoned, Asset Name [Domain]	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'
Number of mining complexes operated	4

Discontinued_Operations_Narrat

Discontinued Operations (Narrative) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Discontinued Operations and Disposal Groups [Abstract]	'	'
Proceeds from sale of Canyon Fuel	$422,663	'

Discontinued_Operations_Schedu

Discontinued Operations (Schedule of Results of Discontinued Operations) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Discontinued Operations and Disposal Groups [Abstract]	'	'	'	'
Total Revenues	$45,763	$112,448	$219,002	$289,715
Income from discontinued operations before income taxes	3,429	16,718	32,166	50,911
Gain on sale	115,679	'	115,679	'
Income tax expense (benefit)	39,704	-4,360	46,029	7,293
Income from discontinued operations, including gain on sale - net of tax	$79,404	$21,078	$101,816	$43,618
Basic earnings per common share from discontinued operations	$0.37	$0.10	$0.48	$0.21
Diluted earnings per common share from discontinued operations	$0.37	$0.10	$0.48	$0.21

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2012	($16,507)
Unrealized gains	7,788
Amounts reclassified from accumulated other comprehensive income	113
Balance at September 30, 2013	-8,606
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2012	2,244
Unrealized gains	1,197
Amounts reclassified from accumulated other comprehensive income	-1,339
Balance at September 30, 2013	2,102
Accumulated Defined Benefit Plans Adjustment [Member]	'
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2012	-18,286
Unrealized gains	1,938
Amounts reclassified from accumulated other comprehensive income	1,252
Balance at September 30, 2013	-15,096
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]	'
Balance at December 31, 2012	-465
Unrealized gains	4,653
Amounts reclassified from accumulated other comprehensive income	200
Balance at September 30, 2013	$4,388

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income (Loss) (Schedule of Reclassifications) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Revenues	$791,269	$975,170	$2,294,971	$2,901,092
Loss from continuing operations before income taxes	-329,680	44,991	-603,168	-694,538
Provision for (benefit from) income taxes	121,913	-20,318	230,734	262,656
Net income (loss)	-128,363	45,751	-270,618	-388,264
reclassification out of accumulated other comprehensive income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Amortization of prior service credits	5,573	'	11,154	'
Amortization of actuarial gains (losses), net	-3,823	'	-13,108	'
Loss from continuing operations before income taxes	1,750	'	-1,954	'
Provision for (benefit from) income taxes	-631	'	702	'
Net income (loss)	1,119	'	-1,252	'
reclassification out of accumulated other comprehensive income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Interest and investment income	-4	'	-313	'
Provision for (benefit from) income taxes	2	'	113	'
Net income (loss)	-2	'	-200	'
Commodity Contract [Member] | reclassification out of accumulated other comprehensive income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Revenues	692	'	2,093	'
Provision for (benefit from) income taxes	-249	'	-754	'
Net income (loss)	$443	'	$1,339	'

Impairment_Charges_Impairment_

Impairment Charges Impairment Charges (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Impaired Long-Lived Assets Held and Used [Line Items]	'	'	'	'
Asset impairment and mine closure costs	$200,397,000	($2,144,000)	$220,879,000	$523,439,000
Impaired Long-Lived Assets Held and Used, Asset Name [Domain]	'	'	'	'
Impaired Long-Lived Assets Held and Used [Line Items]	'	'	'	'
Asset impairment and mine closure costs	'	'	142,800,000	'
Assets, Fair Value Disclosure, Nonrecurring	$71,300,000	'	$71,300,000	'

Inventories_Inventories_Detail

Inventories (Inventories) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]	'	'
Coal	$134,481,000	$180,917,000
Repair parts and supplies	143,763,000	172,139,000
Work-in-process	9,165,000	12,368,000
Inventories	287,409,000	365,424,000
Allowance for slow-moving and obsolete inventories	$8,800,000	$13,600,000

Investments_in_AvailableforSal2

Investments in Available-for-Sale Securities (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	$254,559	$240,382
Gross Unrealized Gains	10,312	2,706
Gross Unrealized Losses	-3,457	-3,436
Fair Value	261,414	239,652
Total Investments	248,724	234,305
US Government Agencies Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	123,809	146,993
Available-for-sale Debt Securities Gross Unrealized Gain	7	2
Available-for-sale Debt Securities, Gross Unrealized Loss	-126	-412
Fair Value	123,690	146,583
Corporate Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	125,479	88,118
Available-for-sale Debt Securities Gross Unrealized Gain	21	'
Available-for-sale Debt Securities, Gross Unrealized Loss	-466	-396
Fair Value	125,034	87,722
Equity Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	5,271	5,271
Available-for-sale Equity Securities, Gross Unrealized Gain	10,284	2,704
Available-for-sale Equity Securities, Gross Unrealized Loss	-2,865	-2,628
Fair Value	12,690	5,347
Short-term Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
U.S. government and agency securities	123,690	146,583
Corporate notes and bonds	125,034	87,722
Total Investments	248,724	234,305
Other Assets [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Equity securities	$12,690	$5,347

Investments_in_AvailableforSal3

Investments in Available-for-Sale Securities (Narrative) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Available-for-sale Securities [Abstract]	'	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$167.50	$223.30
Available-for-sale Securities, Continuous Unrealized Loss Position, Greater than Twelve Months, Fair Value	$51.60	$0.40

Equity_Investments_And_Members2

Equity Investments And Membership Interests In Joint Ventures (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
					Tenaska [Member]	DKRW [Member]	Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'	'
Equity method investment impairment	$200,397,000	($2,144,000)	$220,879,000	$523,439,000	$20,500,000	$57,700,000	'
Impairment of equity investment	'	'	-28,947,000	'	-15,264,000	-13,683,000	'
Note Receivable from Equity Method Investee, Write-downs	'	'	'	'	5,200,000	44,000,000	'
Equity Method Investment, Ownership Percentage	'	'	'	'	35.00%	24.00%	'
Future development costs, maximum limit	'	'	'	'	'	'	$58,500,000

Equity_Investments_And_Members3

Equity Investments And Membership Interests In Joint Ventures (Schedule Of Equity Method Investments) (Details) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2013
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]	'	'
Balance at December 31, 2012	'	$242,215
Advances to (distributions from) affiliates, net	'	4,845
Equity in comprehensive income (loss)	'	-5,441
Impairment of equity investment	'	-28,947
Balance at September 30, 2013	'	223,554
Knight Hawk [Member]	'	'
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]	'	'
Balance at December 31, 2012	'	149,063
Advances to (distributions from) affiliates, net	'	-5,342
Equity in comprehensive income (loss)	'	-13,362
Impairment of equity investment	'	'
Balance at September 30, 2013	'	157,083
DKRW [Member]	'	'
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]	'	'
Balance at December 31, 2012	'	15,515
Advances to (distributions from) affiliates, net	'	'
Equity in comprehensive income (loss)	'	1,832
Impairment of equity investment	'	-13,683
Balance at September 30, 2013	'	'
DTA [Member]	'	'
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]	'	'
Balance at December 31, 2012	'	15,462
Advances to (distributions from) affiliates, net	'	2,537
Equity in comprehensive income (loss)	'	3,855
Impairment of equity investment	'	'
Balance at September 30, 2013	'	14,144
Tenaska [Member]	'	'
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]	'	'
Balance at December 31, 2012	'	15,264
Advances to (distributions from) affiliates, net	'	'
Equity in comprehensive income (loss)	'	'
Impairment of equity investment	-15,264	'
Balance at September 30, 2013	'	'
Millennium [Member]	'	'
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]	'	'
Balance at December 31, 2012	'	32,214
Advances to (distributions from) affiliates, net	'	4,954
Equity in comprehensive income (loss)	'	1,953
Impairment of equity investment	'	'
Balance at September 30, 2013	'	35,215
Tongue River [Member]	'	'
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]	'	'
Balance at December 31, 2012	'	14,697
Advances to (distributions from) affiliates, net	'	2,696
Equity in comprehensive income (loss)	'	281
Impairment of equity investment	'	'
Balance at September 30, 2013	'	$17,112

Derivatives_Narrative_Details

Derivatives (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Derivative [Line Items]	'	'	'	'	'
Current asset (liability) for the right to reclaim cash collateral	($4,900,000)	'	($4,900,000)	'	$16,200,000
Net unrealized and realized gains (losses) related to trading portfolio	900,000	5,500,000	3,000,000	6,200,000	'
Gain on derivative contracts designated as hedge instruments in cash flow hedges to be reclassified from OCI into earnings during the next twelve months	2,900,000	'	2,900,000	'	'
Net derivative assets as classified in the balance sheet	27,061,000	'	27,061,000	'	32,315,000
Year One [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Value of trading portfolio realized	'	'	400,000	'	'
Year Two [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Value of trading portfolio realized	'	'	$7,000,000	'	'
Diesel Purchases [Member] | Year One [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Percent of expected requirements covered	94.00%	'	94.00%	'	'
Diesel Purchases [Member] | Year Two [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Percent of expected requirements covered	82.00%	'	82.00%	'	'
Diesel Purchases [Member] | Heating Oil [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Quantities under derivative contracts	65,000,000	'	65,000,000	'	'
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	2,800,000	'	2,800,000	'	'
Diesel Usage Fuel Surcharges [Member] | Heating Oil [Member] | Year Two [Member]	'	'	'	'	'
Derivative [Line Items]	'	'	'	'	'
Quantities under derivative contracts	4,000,000	'	4,000,000	'	'

Derivatives_Schedule_of_Price_

Derivatives (Schedule of Price Risk Derivatives) (Details)	Sep. 30, 2013
Coal Sales [Member]	'
Derivative [Line Items]	'
Derivatives Held	7,552,000
Coal Purchases [Member]	'
Derivative [Line Items]	'
Derivatives Held	1,869,000
Year One [Member] | Coal Sales [Member]	'
Derivative [Line Items]	'
Derivatives Held	2,314,000
Year One [Member] | Coal Purchases [Member]	'
Derivative [Line Items]	'
Derivatives Held	609,000
Year Two [Member] | Coal Sales [Member]	'
Derivative [Line Items]	'
Derivatives Held	4,458,000
Year Two [Member] | Coal Purchases [Member]	'
Derivative [Line Items]	'
Derivatives Held	1,260,000
Year Three [Member] | Coal Sales [Member]	'
Derivative [Line Items]	'
Derivatives Held	780,000
Year Three [Member] | Coal Purchases [Member]	'
Derivative [Line Items]	'
Derivatives Held	'

Derivatives_Disclosure_Of_Fair

Derivatives (Disclosure Of Fair Value Of Derivatives) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivative [Line Items]	'	'
Derivative Assets	$82,930	$54,863
Derivative Liabilities	-56,290	-24,285
Effect of counterparty netting in derivative assets	-55,869	-22,548
Effect of counterparty netting in derivative liabilities	55,869	22,548
Net derivative assets as classified in the balance sheet	27,061	32,315
Net derivative liabilities as classified in the balance sheet	-421	-1,737
Net derivatives as classified in the balance sheet	26,640	30,578
Designated as Hedging Instrument [Member] | Coal [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	3,009	3,277
Derivative Liabilities	-4	-10
Not Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	79,921	51,586
Derivative Liabilities	-56,286	-24,275
Not Designated as Hedging Instrument [Member] | Coal [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	15,907	24,843
Derivative Liabilities	-3,903	-7,342
Not Designated as Hedging Instrument [Member] | Coal Held for Trading Purposes [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	59,789	17,403
Derivative Liabilities	-52,383	-16,933
Not Designated as Hedging Instrument [Member] | Heating Oil-Diesel Purchases [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	3,825	7,379
Derivative Liabilities	'	'
Not Designated as Hedging Instrument [Member] | Heating Oil-Fuel Surchages [Member]	'	'
Derivative [Line Items]	'	'
Derivative Assets	400	1,961
Derivative Liabilities	'	'

Derivatives_Net_Derivatives_As

Derivatives (Net Derivatives As Reflected On The Balance Sheets) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	$26,640	$30,578
Other Current Assets [Member] | Heating Oil [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	4,225	9,340
Coal Derivative Assets [Member] | Coal [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	22,836	22,975
Coal Derivative Liabilities [Member] | Coal [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Net derivatives as classified in the balance sheet	($421)	($1,737)

Derivatives_Effects_Of_Derivat

Derivatives (Effects Of Derivatives On Measures Of Financial Performance) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'		'
Gain (Loss) Recognized in OCI (Effective Portion)	$2,190	$81	$1,797	[1]	$3,861	[1]
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	788	542	2,189	[1]	1,552	[1]
Coal Purchases [Member]	'	'	'		'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'		'
Gain (Loss) Recognized in OCI (Effective Portion)	-942	-178	-511	[1]	-1,122	[1]
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	-123	'	-633	[1]	'	[1]
Coal Sales [Member]	'	'	'		'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'		'
Gain (Loss) Recognized in OCI (Effective Portion)	3,132	259	2,308	[2]	4,983	[2]
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	911	542	2,822	[2]	1,552	[2]
Coal [Member]	'	'	'		'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'		'
Unrealized Gain (Loss) on Derivatives	-10,668	-11,328	-5,089	[3]	23,670	[3]
Coal derivative settlements, non-hedging	9,929	14,072	25,725	[4]	25,901	[4]
Heating Oil-Diesel Purchases [Member]	'	'	'		'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'		'
Realized Gains (Losses)	-288	5,184	-9,760	[4]	-16,902	[4]
Heating Oil-Fuel Surchages [Member]	'	'	'		'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'		'
Realized Gains (Losses)	($222)	$1,092	($817)	[4]	($1,140)	[4]
[1]	Cost of sales
[2]	Revenues
[3]	Change in fair value of coal derivatives and coal trading activities, net
[4]	Other operating income, net

Debt_Debt_Details

Debt (Debt) (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]	'	'
Other	$25,912,000	$40,350,000
Total	5,097,434,000	5,118,775,000
Current maturities of debt	23,050,000	32,896,000
Long-term debt	5,074,384,000	5,085,879,000
Available borrowing capacity under lines of credit	204,000,000	'
Loans Payable [Member]	'	'
Debt Instrument [Line Items]	'	'
Term loan ($1.63 billion face value) due 2018	1,617,097,000	1,627,384,000
Debt Instrument, Basis Spread on Variable Rate	4.50%	'
Debt Instrument, Face Amount	1,630,000,000	'
8.75% Senior Notes Due 2016 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior notes	592,646,000	590,999,000
Senior notes interest rate	8.75%	'
Debt Instrument, Face Amount	600,000,000	'
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	361,779,000	360,042,000
Senior notes interest rate	9.88%	'
Debt Instrument, Face Amount	375,000,000	'
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%	'

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013
			Level 3 [Member]	Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'	'
Net unrealized losses related to level 3 financial instruments	'	'	$200,000	$4,800,000
Fair value of senior notes and other long-term debt, including amounts classified as current	$4,500,000,000	$5,000,000,000	'	'

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	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Balance, beginning of period	$3,438	$8,174
Realized and unrealized losses recognized in earnings, net	-570	-9,882
Purchases	1,464	7,317
Issuances	'	-25
Settlements	-238	-1,490
Ending balance	$4,094	$4,094

Fair_Value_Measurements_Summar1

Fair Value Measurements (Summary Of Financial Assets And Liabilities Accounted For At Fair Value) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets:	'	'
Investments in marketable securities	$261,414	$239,652
Derivatives	27,061	32,315
Total assets	288,475	'
Liabilities:	'	'
Coal derivative liabilities	421	1,737
Level 1 [Member]	'	'
Assets:	'	'
Investments in marketable securities	101,338	'
Derivatives	22,750	'
Total assets	124,088	'
Liabilities:	'	'
Coal derivative liabilities	'	'
Level 2 [Member]	'	'
Assets:	'	'
Investments in marketable securities	160,076	'
Derivatives	'	'
Total assets	160,076	'
Liabilities:	'	'
Coal derivative liabilities	204	'
Level 3 [Member]	'	'
Assets:	'	'
Investments in marketable securities	'	'
Derivatives	4,311	'
Total assets	4,311	'
Liabilities:	'	'
Coal derivative liabilities	$217	'

Accrued_Expenses_and_Other_Cur2

Accrued Expenses and Other Current Liabilities (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accrued Expenses and Other Current Liabilities [Abstract]	'	'
Payroll and employee benefits	$68,245	$72,405
Taxes other than income taxes	113,872	121,029
Interest	80,454	42,413
Acquired sales contracts	14,461	14,038
Workers’ compensation	12,215	10,371
Asset retirement obligations	38,895	38,920
Other	20,891	18,842
Accrued Liabilities, Current	$349,033	$318,018

StockBased_Compensation_And_Ot1

Stock-Based Compensation And Other Incentive Plans (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Granted, Common Shares	2,000,000	'
Weighted average exercise price of options granted	$5.23	'
Options granted, weighted average grant date fair value	$2.37	'
Option, weighted average risk free rate	0.65%	'
Option, weighted average dividend yield	2.30%	'
Option, weighted average volatility	66.74%	'
Amounts unpaid under long term incentive plan	$15,000,000	$13,100,000
Stock Option [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Expected life of options	'4 years 6 months	'
Share based awards vesting period	'3 years	'
Restricted Stock [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Share based awards vesting period	'3 years	'
Stock Issued During Period, Shares, Restricted Stock Award, Gross	969,100	'
Stock Issued During Period, Value, Restricted Stock Award, Gross	$5.20	'

Workers_Compensation_Workers_C

Workers' Compensation (Worker's Compensation Expense) (Details) (Workers' Compensation [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Workers' Compensation [Member]	'	'	'	'
Accrued Workers' Compensation [Line Items]	'	'	'	'
Service cost	$363	$419	$1,373	$1,458
Interest cost	709	629	2,022	1,708
Net amortization	262	'	731	-574
Curtailments	816	'	816	1,933
Total net benefit	2,150	1,048	4,942	4,525
Traumatic injury claims and assessments	4,114	7,453	16,263	19,052
Total workers’ compensation expense	$6,264	$8,501	$21,205	$23,577

Employee_Benefit_Plans_Pension

Employee Benefit Plans (Pension And Other Postretirement Benefit Costs) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Pension Plans, Defined Benefit [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	$6,672	$6,156	$21,162	$21,062
Interest cost	3,994	3,683	11,796	11,755
Curtailments	47	'	47	324
Expected return on plan assets	-5,848	-5,508	-17,690	-16,523
Amortization of prior service cost (credit)	-51	273	-152	200
Amortization of other actuarial (gains) losses	3,617	3,248	12,430	11,019
Total net benefit	8,431	7,852	27,593	27,837
Other Postretirement Benefit Plans, Defined Benefit [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	497	541	1,591	1,629
Interest cost	427	508	1,273	1,519
Curtailments	-5,444	-2,212	-5,444	-4,049
Amortization of prior service cost (credit)	-2,641	-2,837	-8,121	-8,708
Amortization of other actuarial (gains) losses	-55	-130	-53	-391
Total net benefit	($7,216)	($4,130)	($10,754)	($10,000)

Earnings_Per_Common_Share_Narr

Earnings Per Common Share (Narrative) (Details)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Effect of options to purchase common stock	7	5.8	7.9	5

Settlement_with_Patriot_Coal_D

Settlement with Patriot Coal (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Subsequent Event [Line Items]	'
Payments for Legal Settlements	$15.60
Purchase commitment, remaining minimum amount committed	16
Letters of credit posted in the Companys favor	16.7
Subsequent Event [Member]	'
Subsequent Event [Line Items]	'
Payments for Legal Settlements	$5

Commitments_and_Contingencies_

Commitments and Contingencies (Narrative) (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Aug. 25, 2011	Aug. 13, 2007
Purchase replacement coal	'	'	'	$100
Damages and interest awarded	'	'	104.1	'
Payments for Legal Settlements	15.6	'	'	'
Amount accrued	21.2	32.8	'	'
Amount accrued current portion	7.7	4.4	'	'
Maximum [Member]	'	'	'	'
Aggregate amount of past and future damages	377	'	'	'
Minimum [Member]	'	'	'	'
Aggregate amount of past and future damages	228	'	'	'
past damages [Member]	'	'	'	'
Damages and interest awarded	'	'	13.8	'
future damages [Member]	'	'	'	'
Damages and interest awarded	'	'	$90.30	'

Segment_Information_Narrative_

Segment Information (Narrative) (Details)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Segment Reporting, Factors Used to Identify Entity's Reportable Segments	3

Segment_Information_Schedule_O

Segment Information (Schedule Of Operating Segment Results) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	$791,269	$975,170	$2,294,971	$2,901,092	'
Income (loss) from operations	-234,753	119,242	-322,463	-449,854	'
Depreciation, depletion and amortization	106,323	118,942	327,601	374,631	'
Amortization of acquired sales contracts, net	-2,568	-4,093	-7,587	-22,561	'
Asset impairment and mine closure costs	200,397	-2,144	220,879	523,439	'
Total assets	9,531,455	9,935,854	9,531,455	9,935,854	10,006,777
Capital expenditures	54,104	101,895	223,168	303,968	'
PRB [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	420,521	406,719	1,135,892	1,130,408	'
Income (loss) from operations	20,694	38,873	53,244	94,163	'
Depreciation, depletion and amortization	46,619	43,944	130,993	122,298	'
Amortization of acquired sales contracts, net	-864	-589	-3,004	-1,374	'
Asset impairment and mine closure costs	'	'	'	'	'
Total assets	1,897,218	2,234,941	1,897,218	2,234,941	'
Capital expenditures	1,695	5,620	5,671	15,399	'
APP [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	263,188	436,409	883,484	1,409,776	'
Income (loss) from operations	-157,883	88,695	-190,278	-388,563	'
Depreciation, depletion and amortization	46,529	61,596	157,866	210,789	'
Amortization of acquired sales contracts, net	-2,691	-3,711	-7,975	-21,658	'
Asset impairment and mine closure costs	126,449	-1,801	126,449	524,115	'
Total assets	4,141,072	4,130,273	4,141,072	4,130,273	'
Capital expenditures	44,624	77,772	137,390	222,177	'
WBIT [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	78,022	105,515	187,374	272,359	'
Income (loss) from operations	9,287	24,110	23,766	34,937	'
Depreciation, depletion and amortization	9,436	9,985	26,528	29,894	'
Amortization of acquired sales contracts, net	'	'	'	'	'
Asset impairment and mine closure costs	'	'	'	'	'
Total assets	146,947	676,057	146,947	676,057	'
Capital expenditures	5,859	13,510	13,147	42,761	'
Other Segments [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	29,538	26,527	88,221	88,549	'
Income (loss) from operations	-9,231	-1,298	-407	-3,757	'
Depreciation, depletion and amortization	2,523	2,594	7,792	9,704	'
Amortization of acquired sales contracts, net	987	207	3,392	471	'
Asset impairment and mine closure costs	16,280	-210	16,280	-437	'
Total assets	137,941	169,981	137,941	169,981	'
Capital expenditures	1,263	3,640	4,776	8,153	'
Corporate, Other and Eliminations [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	'	'	'	'	'
Income (loss) from operations	-97,620	-31,138	-208,788	-186,634	'
Depreciation, depletion and amortization	1,216	823	4,422	1,946	'
Amortization of acquired sales contracts, net	'	'	'	'	'
Asset impairment and mine closure costs	57,668	-133	78,150	-239	'
Total assets	3,208,277	2,724,602	3,208,277	2,724,602	'
Capital expenditures	$663	$1,353	$62,184	$15,478	'

Segment_Information_Reconcilia

Segment Information (Reconciliation Statement Of Segment Income from Operations To Consolidated Income Before Income Taxes) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting [Abstract]	'	'	'	'
Income (loss) from operations	($234,753)	$119,242	($322,463)	($449,854)
Interest expense	-95,624	-75,710	-285,454	-229,210
Interest and investment income	697	1,459	4,749	3,568
Other nonoperating expenses	'	'	'	-19,042
Income (loss) from continuing operations before income taxes	($329,680)	$44,991	($603,168)	($694,538)

Supplemental_Condensed_Consoli2

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Operations) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statement Line Items	'	'	'	'
Revenues	$791,269	$975,170	$2,294,971	$2,901,092
Costs, expenses and other	'	'	'	'
Cost of sales (exclusive of items shown separately below)	688,712	808,489	1,994,653	2,414,306
Depreciation, depletion and amortization	106,323	118,942	327,601	374,631
Amortization of acquired sales contracts, net	-2,568	-4,093	-7,587	-22,561
Change in fair value of coal derivatives and coal trading activities, net	9,753	5,840	2,053	-29,827
Asset impairment and mine closure costs	200,397	-2,144	220,879	523,439
Legal contingencies	'	-79,532	'	-79,532
Goodwill impairment	'	'	'	115,791
Selling, general and administrative expenses	28,800	33,266	96,311	99,305
Other operating income, net	-5,395	-24,840	-16,476	-44,606
Operating Expenses	1,026,022	855,928	2,617,434	3,350,946
Loss from investment in subsidiaries	'	'	'	'
Income (loss) from operations	-234,753	119,242	-322,463	-449,854
Interest expense, net	'	'	'	'
Interest expense	-95,624	-75,710	-285,454	-229,210
Interest and investment income	697	1,459	4,749	3,568
Interest expense, net	-94,927	-74,251	-280,705	-225,642
Other Nonoperating Income (Expense) [Abstract]	'	'	'	'
Net loss resulting from early retirement and refinancing of debt	'	'	'	-19,042
Income (loss) before income taxes	-329,680	44,991	-603,168	-694,538
Provision for (benefit from) income taxes	-121,913	20,318	-230,734	-262,656
Income (Loss) from Continuing Operations	-207,767	24,673	-372,434	-431,882
Income from discontinued operations, including gain on sale - net of tax	79,404	21,078	101,816	43,618
Net income (loss)	-128,363	45,751	-270,618	-388,264
Less: Net income attributable to noncontrolling interest	'	'	'	-268
Net income (loss) attributable to Arch Coal, Inc.	-128,363	45,751	-270,618	-388,532
Total comprehensive income (loss)	-125,996	44,299	-262,717	-385,523
Parent/Issuer [Member]	'	'	'	'
Condensed Financial Statement Line Items	'	'	'	'
Revenues	'	'	'	'
Costs, expenses and other	'	'	'	'
Cost of sales (exclusive of items shown separately below)	169	2,437	4,881	7,694
Depreciation, depletion and amortization	1,549	1,399	4,430	3,959
Amortization of acquired sales contracts, net	'	'	'	'
Change in fair value of coal derivatives and coal trading activities, net	'	'	'	'
Asset impairment and mine closure costs	57,668	'	78,150	'
Legal contingencies	'	'	'	'
Goodwill impairment	'	'	'	'
Selling, general and administrative expenses	19,104	22,051	63,006	62,469
Other operating income, net	2,345	-11,052	-4,663	-7,693
Operating Expenses	80,835	14,835	145,804	66,429
Loss from investment in subsidiaries	-61,537	164,152	-42,199	-324,429
Income (loss) from operations	-142,372	149,317	-188,003	-390,858
Interest expense, net	'	'	'	'
Interest expense	-114,536	-91,577	-336,310	-263,381
Interest and investment income	6,606	8,329	22,917	19,087
Interest expense, net	-107,930	-83,248	-313,393	-244,294
Other Nonoperating Income (Expense) [Abstract]	'	'	'	'
Net loss resulting from early retirement and refinancing of debt	'	'	'	-17,349
Income (loss) before income taxes	-250,302	66,069	-501,396	-652,501
Provision for (benefit from) income taxes	-121,939	20,318	-230,778	-264,237
Income (Loss) from Continuing Operations	-128,363	45,751	-270,618	-388,264
Income from discontinued operations, including gain on sale - net of tax	'	'	'	'
Net income (loss)	'	'	'	-388,264
Less: Net income attributable to noncontrolling interest	'	'	'	-268
Net income (loss) attributable to Arch Coal, Inc.	-128,363	45,751	-270,618	-388,532
Total comprehensive income (loss)	-125,996	44,299	-262,717	-385,523
Guarantor Subsidiaries [Member]	'	'	'	'
Condensed Financial Statement Line Items	'	'	'	'
Revenues	791,269	975,170	2,294,971	2,901,092
Costs, expenses and other	'	'	'	'
Cost of sales (exclusive of items shown separately below)	688,543	806,052	1,989,772	2,406,612
Depreciation, depletion and amortization	104,765	117,534	323,144	370,648
Amortization of acquired sales contracts, net	-2,568	-4,093	-7,587	-22,561
Change in fair value of coal derivatives and coal trading activities, net	9,753	5,840	2,053	-29,827
Asset impairment and mine closure costs	142,729	-2,144	142,729	523,439
Legal contingencies	'	-79,532	'	-79,532
Goodwill impairment	'	'	'	115,791
Selling, general and administrative expenses	8,214	9,432	28,978	30,965
Other operating income, net	-7,740	-13,699	-10,704	-23,811
Operating Expenses	943,696	839,390	2,468,385	3,291,724
Loss from investment in subsidiaries	'	'	'	'
Income (loss) from operations	-152,427	135,780	-173,414	-390,632
Interest expense, net	'	'	'	'
Interest expense	-6,222	-6,870	-18,502	-27,285
Interest and investment income	18,975	14,570	49,986	42,508
Interest expense, net	12,753	7,700	31,484	15,223
Other Nonoperating Income (Expense) [Abstract]	'	'	'	'
Net loss resulting from early retirement and refinancing of debt	'	'	'	-1,693
Income (loss) before income taxes	-139,674	143,480	-141,930	-377,102
Provision for (benefit from) income taxes	'	'	'	'
Income (Loss) from Continuing Operations	-139,674	143,480	-141,930	-377,102
Income from discontinued operations, including gain on sale - net of tax	79,404	21,078	101,816	43,618
Net income (loss)	'	'	'	-333,484
Less: Net income attributable to noncontrolling interest	'	'	'	'
Net income (loss) attributable to Arch Coal, Inc.	-60,270	164,558	-40,114	-333,484
Total comprehensive income (loss)	-59,241	163,375	-39,175	-336,648
Non-Guarantor Subsidiaries [Member]	'	'	'	'
Condensed Financial Statement Line Items	'	'	'	'
Revenues	'	'	'	'
Costs, expenses and other	'	'	'	'
Cost of sales (exclusive of items shown separately below)	'	'	'	'
Depreciation, depletion and amortization	9	9	27	24
Amortization of acquired sales contracts, net	'	'	'	'
Change in fair value of coal derivatives and coal trading activities, net	'	'	'	'
Asset impairment and mine closure costs	'	'	'	'
Legal contingencies	'	'	'	'
Goodwill impairment	'	'	'	'
Selling, general and administrative expenses	1,482	1,783	4,327	5,871
Other operating income, net	'	-89	-1,109	-13,102
Operating Expenses	1,491	1,703	3,245	-7,207
Loss from investment in subsidiaries	'	'	'	'
Income (loss) from operations	-1,491	-1,703	-3,245	7,207
Interest expense, net	'	'	'	'
Interest expense	-1,070	-649	-3,170	-2,382
Interest and investment income	1,320	1,946	4,374	5,811
Interest expense, net	250	1,297	1,204	3,429
Other Nonoperating Income (Expense) [Abstract]	'	'	'	'
Net loss resulting from early retirement and refinancing of debt	'	'	'	'
Income (loss) before income taxes	-1,241	-406	-2,041	10,636
Provision for (benefit from) income taxes	26	'	44	1,581
Income (Loss) from Continuing Operations	-1,267	-406	-2,085	9,055
Income from discontinued operations, including gain on sale - net of tax	'	'	'	'
Net income (loss)	'	'	'	9,055
Less: Net income attributable to noncontrolling interest	'	'	'	'
Net income (loss) attributable to Arch Coal, Inc.	-1,267	-406	-2,085	9,055
Total comprehensive income (loss)	-1,267	-406	-2,085	9,055
Eliminations [Member]	'	'	'	'
Condensed Financial Statement Line Items	'	'	'	'
Revenues	'	'	'	'
Costs, expenses and other	'	'	'	'
Cost of sales (exclusive of items shown separately below)	'	'	'	'
Depreciation, depletion and amortization	'	'	'	'
Amortization of acquired sales contracts, net	'	'	'	'
Change in fair value of coal derivatives and coal trading activities, net	'	'	'	'
Asset impairment and mine closure costs	'	'	'	'
Legal contingencies	'	'	'	'
Goodwill impairment	'	'	'	'
Selling, general and administrative expenses	'	'	'	'
Other operating income, net	'	'	'	'
Operating Expenses	'	'	'	'
Loss from investment in subsidiaries	61,537	-164,152	42,199	324,429
Income (loss) from operations	61,537	-164,152	42,199	324,429
Interest expense, net	'	'	'	'
Interest expense	26,204	23,386	72,528	63,838
Interest and investment income	-26,204	-23,386	-72,528	-63,838
Interest expense, net	'	'	'	'
Other Nonoperating Income (Expense) [Abstract]	'	'	'	'
Net loss resulting from early retirement and refinancing of debt	'	'	'	'
Income (loss) before income taxes	61,537	-164,152	42,199	324,429
Provision for (benefit from) income taxes	'	'	'	'
Income (Loss) from Continuing Operations	61,537	-164,152	42,199	324,429
Income from discontinued operations, including gain on sale - net of tax	'	'	'	'
Net income (loss)	'	'	'	324,429
Less: Net income attributable to noncontrolling interest	'	'	'	'
Net income (loss) attributable to Arch Coal, Inc.	61,537	-164,152	42,199	324,429
Total comprehensive income (loss)	$60,508	($162,969)	$41,260	$327,593

Supplemental_Condensed_Consoli3

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Balance Sheets) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Assets	'	'	'	'
Cash and cash equivalents	$1,133,128	$784,622	$550,756	$138,149
Restricted cash	'	3,453	'	'
Short term investments	248,724	234,305	'	'
Receivables	214,839	332,080	'	'
Inventories	287,409	365,424	'	'
Other	145,539	194,220	'	'
Total current assets	2,029,639	1,914,104	'	'
Property, plant and equipment, net	6,778,225	7,337,098	'	'
Investment in subsidiaries	'	'	'	'
Intercompany receivables	'	'	'	'
Note receivable from Arch Western	'	'	'	'
Other	723,591	755,575	'	'
Assets, Noncurrent	723,591	755,575	'	'
Total assets	9,531,455	10,006,777	9,935,854	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	207,273	224,418	'	'
Accrued expenses and other current liabilities	349,454	319,755	'	'
Current maturities of debt	23,050	32,896	'	'
Total current liabilities	579,777	577,069	'	'
Long-term debt	5,074,384	5,085,879	'	'
Intercompany payables	'	'	'	'
Note payable to Arch Coal	'	'	'	'
Asset retirement obligations	411,121	409,705	'	'
Accrued pension benefits	68,539	67,630	'	'
Accrued postretirement benefits other than pension	44,279	45,086	'	'
Accrued workers’ compensation	82,014	81,629	'	'
Deferred income taxes	484,130	664,182	'	'
Other noncurrent liabilities	205,557	221,030	'	'
Total liabilities	6,949,801	7,152,210	'	'
Stockholders' equity	2,581,654	2,854,567	'	'
Total liabilities and stockholders’ equity	9,531,455	10,006,777	'	'
Parent/Issuer [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	1,021,245	671,313	313,548	66,542
Restricted cash	'	3,453	'	'
Short term investments	248,724	234,305	'	'
Receivables	7,847	49,281	'	'
Inventories	'	'	'	'
Other	96,992	106,786	'	'
Total current assets	1,374,808	1,065,138	'	'
Property, plant and equipment, net	25,526	27,476	'	'
Investment in subsidiaries	7,992,601	8,254,508	'	'
Intercompany receivables	'	'	'	'
Note receivable from Arch Western	675,000	675,000	'	'
Other	147,950	187,171	'	'
Assets, Noncurrent	8,815,551	9,116,679	'	'
Total assets	10,215,885	10,209,293	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	20,728	19,859	'	'
Accrued expenses and other current liabilities	107,756	65,293	'	'
Current maturities of debt	19,343	32,054	'	'
Total current liabilities	147,827	117,206	'	'
Long-term debt	5,055,021	5,061,925	'	'
Intercompany payables	1,810,718	1,367,739	'	'
Note payable to Arch Coal	'	'	'	'
Asset retirement obligations	1,150	1,646	'	'
Accrued pension benefits	36,304	33,456	'	'
Accrued postretirement benefits other than pension	14,267	13,953	'	'
Accrued workers’ compensation	25,601	25,323	'	'
Deferred income taxes	484,130	664,182	'	'
Other noncurrent liabilities	59,179	69,296	'	'
Total liabilities	7,634,197	7,354,726	'	'
Stockholders' equity	2,581,688	2,854,567	'	'
Total liabilities and stockholders’ equity	10,215,885	10,209,293	'	'
Guarantor Subsidiaries [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	100,410	100,468	225,431	70,258
Restricted cash	'	'	'	'
Short term investments	'	'	'	'
Receivables	21,178	40,452	'	'
Inventories	287,409	365,424	'	'
Other	48,270	86,877	'	'
Total current assets	457,267	593,221	'	'
Property, plant and equipment, net	6,752,687	7,309,550	'	'
Investment in subsidiaries	'	'	'	'
Intercompany receivables	1,986,992	1,600,311	'	'
Note receivable from Arch Western	'	'	'	'
Other	575,551	568,314	'	'
Assets, Noncurrent	2,562,543	2,168,625	'	'
Total assets	9,772,497	10,071,396	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	186,468	204,370	'	'
Accrued expenses and other current liabilities	246,063	259,162	'	'
Current maturities of debt	3,707	842	'	'
Total current liabilities	436,238	464,374	'	'
Long-term debt	19,363	23,954	'	'
Intercompany payables	'	'	'	'
Note payable to Arch Coal	675,000	675,000	'	'
Asset retirement obligations	409,971	408,059	'	'
Accrued pension benefits	32,235	34,174	'	'
Accrued postretirement benefits other than pension	30,012	31,133	'	'
Accrued workers’ compensation	56,413	56,306	'	'
Deferred income taxes	'	'	'	'
Other noncurrent liabilities	146,055	151,360	'	'
Total liabilities	1,805,287	1,844,360	'	'
Stockholders' equity	7,967,210	8,227,036	'	'
Total liabilities and stockholders’ equity	9,772,497	10,071,396	'	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	11,473	12,841	11,777	1,349
Restricted cash	'	'	'	'
Short term investments	'	'	'	'
Receivables	190,493	247,171	'	'
Inventories	'	'	'	'
Other	277	557	'	'
Total current assets	202,243	260,569	'	'
Property, plant and equipment, net	46	72	'	'
Investment in subsidiaries	'	'	'	'
Intercompany receivables	'	'	'	'
Note receivable from Arch Western	'	'	'	'
Other	90	90	'	'
Assets, Noncurrent	90	90	'	'
Total assets	202,379	260,731	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	77	189	'	'
Accrued expenses and other current liabilities	314	124	'	'
Current maturities of debt	'	'	'	'
Total current liabilities	391	313	'	'
Long-term debt	'	'	'	'
Intercompany payables	176,274	232,572	'	'
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	323	374	'	'
Total liabilities	176,988	233,259	'	'
Stockholders' equity	25,391	27,472	'	'
Total liabilities and stockholders’ equity	202,379	260,731	'	'
Eliminations [Member]	'	'	'	'
Assets	'	'	'	'
Cash and cash equivalents	'	'	'	'
Restricted cash	'	'	'	'
Short term investments	'	'	'	'
Receivables	-4,679	-4,824	'	'
Inventories	'	'	'	'
Other	'	'	'	'
Total current assets	-4,679	-4,824	'	'
Property, plant and equipment, net	-34	'	'	'
Investment in subsidiaries	-7,992,601	-8,254,508	'	'
Intercompany receivables	-1,986,992	-1,600,311	'	'
Note receivable from Arch Western	-675,000	-675,000	'	'
Other	'	'	'	'
Assets, Noncurrent	-10,654,593	-10,529,819	'	'
Total assets	-10,659,306	-10,534,643	'	'
Liabilities and Stockholders’ Equity	'	'	'	'
Accounts payable	'	'	'	'
Accrued expenses and other current liabilities	-4,679	-4,824	'	'
Current maturities of debt	'	'	'	'
Total current liabilities	-4,679	-4,824	'	'
Long-term debt	'	'	'	'
Intercompany payables	-1,986,992	-1,600,311	'	'
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	-2,666,671	-2,280,135	'	'
Stockholders' equity	-7,992,635	-8,254,508	'	'
Total liabilities and stockholders’ equity	($10,659,306)	($10,534,643)	'	'

Supplemental_Condensed_Consoli4

Supplemental Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Cash Flows) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash provided by (used in) operating activities	$186,592	$356,395
Investing Activities	'	'
Capital expenditures	-223,168	-303,968
Minimum royalty payments	-10,901	-9,192
Proceeds from dispositions of property, plant and equipment	8,799	22,624
Proceeds from sale-leaseback transactions	34,919	'
Proceeds from sale of Canyon Fuel	422,663	'
Purchases of short term investments	-85,418	-99,628
Proceeds from sales of short term investments	67,255	'
Investments in and advances to affiliates	-11,124	-12,685
Purchase of noncontrolling interest	'	-17,500
Change in restricted cash	3,453	6,872
Cash provided by (used in) investing activities	206,478	-413,477
Financing Activities	'	'
Contributions from parent	'	'
Proceeds from issuance of term loan	'	1,386,000
Payments on term loan	-12,375	-3,500
Payments to retire debt	-384	-452,806
Net decrease in borrowings under lines of credit	'	-381,300
Net payments on other debt	-12,700	-13,078
Debt financing costs	'	-34,686
Dividends paid	-19,105	-36,072
Proceeds from exercise of options under incentive plans	'	5,131
Transactions with affiliates, net	'	'
Cash provided by (used in) financing activities	-44,564	469,689
Increase (decrease) in cash and cash equivalents	348,506	412,607
Cash and cash equivalents, beginning of period	784,622	138,149
Cash and cash equivalents, end of period	1,133,128	550,756
Parent/Issuer [Member]	'	'
Cash provided by (used in) operating activities	-22,206	-610,129
Investing Activities	'	'
Capital expenditures	-2,488	-4,150
Minimum royalty payments	'	'
Proceeds from dispositions of property, plant and equipment	'	'
Proceeds from sale-leaseback transactions	'	'
Proceeds from sale of Canyon Fuel	'	'
Purchases of short term investments	-85,418	-99,628
Proceeds from sales of short term investments	67,255	'
Investments in and advances to affiliates	-4,016	-5,138
Purchase of noncontrolling interest	'	'
Change in restricted cash	3,453	6,872
Cash provided by (used in) investing activities	-21,214	-102,044
Financing Activities	'	'
Contributions from parent	'	'
Proceeds from issuance of term loan	'	1,386,000
Payments on term loan	-12,375	-3,500
Payments to retire debt	'	'
Net decrease in borrowings under lines of credit	'	-375,000
Net payments on other debt	-12,700	-13,078
Debt financing costs	'	-34,640
Dividends paid	-19,105	-36,072
Proceeds from exercise of options under incentive plans	'	5,131
Transactions with affiliates, net	437,532	30,338
Cash provided by (used in) financing activities	393,352	959,179
Increase (decrease) in cash and cash equivalents	349,932	247,006
Cash and cash equivalents, beginning of period	671,313	66,542
Cash and cash equivalents, end of period	1,021,245	313,548
Guarantor Subsidiaries [Member]	'	'
Cash provided by (used in) operating activities	153,868	874,545
Investing Activities	'	'
Capital expenditures	-220,680	-299,818
Minimum royalty payments	-10,901	-9,192
Proceeds from dispositions of property, plant and equipment	8,799	1,127
Proceeds from sale-leaseback transactions	34,919	'
Proceeds from sale of Canyon Fuel	422,663	'
Purchases of short term investments	'	'
Proceeds from sales of short term investments	'	'
Investments in and advances to affiliates	-7,492	-9,082
Purchase of noncontrolling interest	'	-17,500
Change in restricted cash	'	'
Cash provided by (used in) investing activities	227,308	-334,465
Financing Activities	'	'
Contributions from parent	384	1,535
Proceeds from issuance of term loan	'	'
Payments on term loan	'	'
Payments to retire debt	-384	-452,806
Net decrease in borrowings under lines of credit	'	'
Net payments on other debt	'	'
Debt financing costs	'	'
Dividends paid	'	'
Proceeds from exercise of options under incentive plans	'	'
Transactions with affiliates, net	-381,234	66,364
Cash provided by (used in) financing activities	-381,234	-384,907
Increase (decrease) in cash and cash equivalents	-58	155,173
Cash and cash equivalents, beginning of period	100,468	70,258
Cash and cash equivalents, end of period	100,410	225,431
Non-Guarantor Subsidiaries [Member]	'	'
Cash provided by (used in) operating activities	54,930	91,979
Investing Activities	'	'
Capital expenditures	'	'
Minimum royalty payments	'	'
Proceeds from dispositions of property, plant and equipment	'	21,497
Proceeds from sale-leaseback transactions	'	'
Proceeds from sale of Canyon Fuel	'	'
Purchases of short term investments	'	'
Proceeds from sales of short term investments	'	'
Investments in and advances to affiliates	'	'
Purchase of noncontrolling interest	'	'
Change in restricted cash	'	'
Cash provided by (used in) investing activities	'	21,497
Financing Activities	'	'
Contributions from parent	'	'
Proceeds from issuance of term loan	'	'
Payments on term loan	'	'
Payments to retire debt	'	'
Net decrease in borrowings under lines of credit	'	-6,300
Net payments on other debt	'	'
Debt financing costs	'	-46
Dividends paid	'	'
Proceeds from exercise of options under incentive plans	'	'
Transactions with affiliates, net	-56,298	-96,702
Cash provided by (used in) financing activities	-56,298	-103,048
Increase (decrease) in cash and cash equivalents	-1,368	10,428
Cash and cash equivalents, beginning of period	12,841	1,349
Cash and cash equivalents, end of period	11,473	11,777
Eliminations [Member]	'	'
Cash provided by (used in) operating activities	'	'
Investing Activities	'	'
Capital expenditures	'	'
Minimum royalty payments	'	'
Proceeds from dispositions of property, plant and equipment	'	'
Proceeds from sale-leaseback transactions	'	'
Proceeds from sale of Canyon Fuel	'	'
Purchases of short term investments	'	'
Proceeds from sales of short term investments	'	'
Investments in and advances to affiliates	384	1,535
Purchase of noncontrolling interest	'	'
Change in restricted cash	'	'
Cash provided by (used in) investing activities	384	1,535
Financing Activities	'	'
Contributions from parent	-384	-1,535
Proceeds from issuance of term loan	'	'
Payments on term loan	'	'
Payments to retire debt	'	'
Net decrease in borrowings under lines of credit	'	'
Net payments on other debt	'	'
Debt financing costs	'	'
Dividends paid	'	'
Proceeds from exercise of options under incentive plans	'	'
Transactions with affiliates, net	'	'
Cash provided by (used in) financing activities	-384	-1,535
Increase (decrease) in cash and cash equivalents	'	'
Cash and cash equivalents, beginning of period	'	'
Cash and cash equivalents, end of period	'	'