Reconciliation of Segment Information, Revenue and Other Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	$ 1,226,165	$ 1,311,471
Earnings Before Income Taxes:
Earnings Before Income Taxes	(1,299)	118,577
Revenue from Purchased Oil and Gas	1,358	839
Sales-Gas Royalty Interests	14,204	12,206
Freight-Outside	14,061	49,293
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	1,255,788	1,373,809
Total Assets	12,593,194	12,595,611	12,670,909
Depreciation, Depletion and Amortization	161,315	155,347
Capital Expenditures	405,972	306,446
Total Reportable Business Segments
Earnings Before Income Taxes:
Earnings Before Income Taxes	92,862	174,970
Total Assets	11,578,492	11,471,162
Coal
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	972,385	1,054,316
Earnings Before Income Taxes:
Earnings Before Income Taxes	93,502	162,470
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	14,061	49,293
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	986,446	1,103,609
Total Assets	5,698,504	5,360,577
Depreciation, Depletion and Amortization	102,711	100,762
Capital Expenditures	197,338	194,429
Gas
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	167,842	160,203
Earnings Before Income Taxes:
Earnings Before Income Taxes	(640)	12,500
Revenue from Purchased Oil and Gas	1,358	839
Sales-Gas Royalty Interests	14,204	12,206
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	836	466
Segment Reporting Information, Revenue for Reportable Segment	184,240	173,714
Total Assets	5,879,988	6,110,585
Depreciation, Depletion and Amortization	52,399	48,803
Capital Expenditures	207,130	98,455
All Other Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	85,938	96,952
Earnings Before Income Taxes:
Earnings Before Income Taxes	(40,552)	4,083
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	35,477	37,209
Segment Reporting Information, Revenue for Reportable Segment	121,415	134,161
Total Assets	358,663	358,746
Depreciation, Depletion and Amortization	6,205	5,782
Capital Expenditures	1,504	13,562
Excludes Gas Segment [Member]
Earnings Before Income Taxes:
Interest Income (Expense), Net and Other Non-operating Activity	(52,660)	(60,042)
Fees for Disposing Non-core Assets	949	434
Intersegment Elimination [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	0	0
Earnings Before Income Taxes:
Earnings Before Income Taxes	(53,609)	(60,476)
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	(36,313)	(37,675)
Segment Reporting Information, Revenue for Reportable Segment	(36,313)	(37,675)
Total Assets	656,039	765,703
Depreciation, Depletion and Amortization	0	0
Capital Expenditures	0	0
Steam [Member] \| Coal
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	761,272	812,053
Earnings Before Income Taxes:
Earnings Before Income Taxes	128,432	128,449
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	761,272	812,053
High Volatile Metallurgical [member] \| Coal
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	58,622	60,568
Earnings Before Income Taxes:
Earnings Before Income Taxes	13,352	15,936
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	58,622	60,568
Low Volatile Metallurgical [Member] \| Coal
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	146,828	172,740
Earnings Before Income Taxes:
Earnings Before Income Taxes	54,717	79,341
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	146,828	172,740
Other Coal [Member] \| Coal
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	5,663	8,955
Earnings Before Income Taxes:
Earnings Before Income Taxes	(102,999)	(61,256)
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	14,061	49,293
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	19,724	58,248
Coalbed Methane [Member] \| Gas
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	83,640	99,535
Earnings Before Income Taxes:
Earnings Before Income Taxes	21,312	36,390
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	83,640	99,535
Marcellus Shale [Member] \| Gas
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	48,411	23,791
Earnings Before Income Taxes:
Earnings Before Income Taxes	13,768	3,251
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	48,411	23,791
Conventional Gas [Member] \| Gas
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	32,436	34,373
Earnings Before Income Taxes:
Earnings Before Income Taxes	(4,161)	(3,722)
Revenue from Purchased Oil and Gas	0	0
Sales-Gas Royalty Interests	0	0
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	0	0
Segment Reporting Information, Revenue for Reportable Segment	32,436	34,373
Other Gas \| Gas
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-Outside	3,355	2,504
Earnings Before Income Taxes:
Earnings Before Income Taxes	(31,559)	(23,419)
Revenue from Purchased Oil and Gas	1,358	839
Sales-Gas Royalty Interests	14,204	12,206
Freight-Outside	0	0
Segment Reporting Information, Intersegment Revenue	836	466
Segment Reporting Information, Revenue for Reportable Segment	19,753	16,015
First Energy [Member] \| Coal
Segment Reporting, Revenue Reconciling Item [Line Items]
Entity-Wide Revenue, Major Customer, Amount	$ 170,982	$ 144,155

Fees for Disposing Non Core Assets

No definition available.

Name:	cnx_FeesForDisposingNonCoreAssets
Namespace Prefix:	cnx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest and Other Nonoperating Income (Expense), Net

+ References

No definition available.

+ Details

Name:	cnx_InterestAndOtherNonoperatingIncomeExpenseNet
Namespace Prefix:	cnx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Revenue from the sale of oil and gas which is sold by CNX on behalf of the royalty owner.

+ References

No definition available.

+ Details

Name:	cnx_RoyaltyInterestGasRevenue
Namespace Prefix:	cnx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total expenditures for additions to long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets of the reportable segment; if the amount: (a) is included in the determination of segment assets reviewed by the chief operating decision maker or (b) is otherwise regularly provided to the chief operating decision maker, even if not included in the determination of segment assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 28

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_AdditionsToNoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Concepts (CON)

-Number 6

-Paragraph 25

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 18

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.18)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_Assets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Revenue from transporting cargo and freight between locations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-AIR

-Paragraph 4

-IssueDate 2003-05-01

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_CargoAndFreightRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

+ Details

Name:	us-gaap_DepreciationDepletionAndAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 42

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 39

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_EntityWideRevenueMajorCustomerAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h)(1)(i))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Subparagraph 1(i)

-Article 4

+ Details

Name:	us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestmentsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Revenue from sale of oil and gas purchased from other sources.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 235

-Section 50

-Paragraph 23

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 235

-Section 50

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62246-109447

+ Details

Name:	us-gaap_RevenueFromPurchasedOilAndGas
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate revenue from the sale of minerals and related products, and from rendering services such as exploration, development, mining, processing and providing mining support activities.

+ References

+ Details

Name:	us-gaap_RevenueMineralSales
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue from transactions with other operating segments of the same entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 22

-Subparagraph (a),(b),(c)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a, b, c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_SegmentReportingInformationRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_SegmentReportingRevenueReconcilingItemLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration