Contribution by affiliate for general and administrative expenses.

No definition available.

Name:	arlp_ContributionByAffiliate
Namespace Prefix:	arlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

General and administrative expenses allocated to the general partner in connection with capital contributions received for the purpose of funding these expenses.

+ References

No definition available.

+ Details

Name:	arlp_GeneralAndAdministrativeExpensesAllocatedToGeneralPartner
Namespace Prefix:	arlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate amount of net income allocated to general partners based on equity ownership percentage, as an adjustment to derive net income allocated to limited partners.

+ References

No definition available.

+ Details

Name:	arlp_NetIncomeLossAllocatedToGeneralPartnersForEquityOwnershipPercentage
Namespace Prefix:	arlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Aggregate amount of net income available to limited partners after allocation to participating securities.

+ References

No definition available.

+ Details

Name:	arlp_NetIncomeLossOfRegistrantAllocatedToLimitedPartners
Namespace Prefix:	arlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Pro forma adjustment to the net income (loss) for the period.

+ References

No definition available.

+ Details

Name:	arlp_NetIncomeLossProformaAdjustment
Namespace Prefix:	arlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of common units issued in an exchange transaction.

+ References

No definition available.

+ Details

Name:	arlp_NumberOfCommonUnitsIssuedInExchangeTransaction
Namespace Prefix:	arlp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of limited partner units issued to SGP in Simplification Transactions.

+ References

No definition available.

+ Details

Name:	arlp_PartnersCapitalAccountSgpSimplificationTransactionUnits
Namespace Prefix:	arlp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of undistributed earnings (loss) allocated to participating securities for the basic and diluted earnings (loss) per share or per unit calculations under the two-class method.

+ References

No definition available.

+ Details

Name:	arlp_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasicAndDiluted
Namespace Prefix:	arlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of paid and unpaid cash, stock, and paid-in-kind dividends declared for award under share-based payment arrangement.

+ References

No definition available.

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Distributions from earnings to the general partner of a partnership included in the consolidated financial statements.

+ References

No definition available.

+ Details

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

- Definition

Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

+ Details

Name:	us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

+ Details

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

- Definition

Aggregate amount of net income allocated to limited partners.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

+ Details

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

- Definition

The amount of net income or loss for the period per each limited partnership and general partnership unit in instances when basic and diluted earnings per unit are the same amount and aggregated on the face of the financial statements. Basic earnings per unit is the amount of net income or loss for the period per unit outstanding during the reporting period. Diluted earnings per unit includes the amount of net income or loss for the period available to each limited and general partnership unit outstanding during the reporting period and to each unit that would have been outstanding assuming the issuance of units for all dilutive potential units outstanding during the reporting period.

+ References

No definition available.

+ Details

Name:	us-gaap_NetIncomeLossPerOutstandingLimitedPartnershipAndGeneralPartnershipUnitBasicAndDiluted
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The average number of limited partnership and general partnership units issued and outstanding that are used in calculating basic and diluted earnings per limited partnership and general partnership unit.

+ References

No definition available.

+ Details

Name:	us-gaap_WeightedAverageNumberOfLimitedPartnershipAndGeneralPartnershipUnitOutstandingBasicAndDiluted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=arlp_ManagingGeneralPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=arlp_AllianceResourcePartnersLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=arlp_AllianceResourceOperatingPartnersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=arlp_AllianceCoalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ProFormaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherSignificantNoncashTransactionsByUniqueDescriptionAxis=arlp_PrivatePlacementExchangeTransactionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherSignificantNoncashTransactionsByUniqueDescriptionAxis=arlp_MergerAndSimplificationAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=arlp_AllianceHoldingsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=arlp_SpecialGeneralPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=arlp_ManagingGeneralPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

EARNINGS PER LIMITED PARTNER UNIT - Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	May 31, 2018	Jul. 28, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to ARLP			$ 399,414	$ 366,604	$ 303,638
MGP's priority distributions					(19,216)
General partner's equity ownership				(1,560)	(3,688)
General partner's special allocation of certain general and administrative expenses					1,000
LIMITED PARTNERS			399,414	365,044	281,734
Distributions to participating securities			(4,254)	(5,114)	(4,339)
Undistributed earnings attributable to participating securities			(2,237)	(1,641)	(1,026)
Net income attributable to ARLP available to limited partners			$ 392,923	$ 358,289	$ 276,369
Weighted-average limited partner units outstanding - basic and diluted			128,116,670	130,758,169	98,707,696
EARNINGS PER LIMITED PARTNER UNIT - BASIC AND DILUTED			$ 3.07	$ 2.74	$ 2.80
Anti-dilutive under the treasury stock method (in units)			1,284,013	1,658,908	1,466,404
MGP
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Contributions from affiliates for general and administrative expenses					$ 1,000
MGP \| ARLP
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners			0.99%
MGP \| Intermediate Partnership
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners			1.0001%
MGP \| Alliance Coal
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners			0.001%
Pro Forma
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to ARLP			$ 399,414	$ 366,604	303,638
Pro forma adjustments				(1,265)	(1,943)
LIMITED PARTNERS			399,414	365,339	301,695
Distributions to participating securities			(4,254)	(5,114)	(4,339)
Undistributed earnings attributable to participating securities			(2,237)	(1,627)	(680)
Net income attributable to ARLP available to limited partners			$ 392,923	$ 358,598	$ 296,676
Weighted-average limited partner units outstanding - basic and diluted			128,117,000	131,310,000	132,024,000
EARNINGS PER LIMITED PARTNER UNIT - BASIC AND DILUTED			$ 3.07	$ 2.73	$ 2.25
Anti-dilutive under the treasury stock method (in units)			1,284,013	1,658,908	1,466,404
Exchange Transaction
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common units issued in exchange			56,128,141
Exchange Transaction \| MGP \| ARLP
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners		0.99%
Simplification Transactions
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Issuance of units to Owners of SGP in Simplification Transactions (in units)			1,322,388
Simplification Transactions \| Intermediate Partnership
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners	1.0001%
Simplification Transactions \| Alliance Coal
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners	0.001%
Simplification Transactions \| AHGP \| Intermediate Partnership
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners	1.0001%
Simplification Transactions \| AHGP \| Alliance Coal
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners	0.001%
Simplification Transactions \| MGP \| Intermediate Partnership
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners	1.0001%
Simplification Transactions \| MGP \| Alliance Coal
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Ownership percentage by general partners	0.001%
SGP \| Exchange Transaction
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common units issued in exchange		28,141
SGP \| Simplification Transactions
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common units issued in exchange	29,188,997
Issuance of units to Owners of SGP in Simplification Transactions (in units)	1,322,388
MGP \| Exchange Transaction
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common units issued in exchange		56,100,000