The specified internal rate of return to determine distribution percentage, as a percent.

No definition available.

Name:	arlp_DistributionsMadeToMemberOrLimitedPartnerInternalRateOfReturn
Namespace Prefix:	arlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of available cash distributed to members or limited partners of an LLC or LP.

+ References

No definition available.

+ Details

Name:	arlp_DistributionsMadeToMemberOrLimitedPartnerPercentageOfAvailableCash
Namespace Prefix:	arlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The distribution percentage after the hurdles are reached.

+ References

No definition available.

+ Details

Name:	arlp_DistributionsPercentageAfterHurdlesAreReached
Namespace Prefix:	arlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporation; these investments are accounted for under the equity method of accounting. This element includes distributions that constitute a return of investment.

+ References

No definition available.

+ Details

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

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8813-108599

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

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

- Definition

Percentage investment held by members or limited partners of 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_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=arlp_AllDaleMineralsIiiMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

VARIABLE INTEREST ENTITIES - All Dale III (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Feb. 28, 2017
Equity Investments
Investments in affiliate	$ 27,705		$ 27,705			$ 28,529
All Dale Minerals III
Equity Investments
Distribution after hurdles (as a percent)			25.00%
Specified internal rate of return (as a percent)			10.00%
Percentage of available cash distributed			125.00%
All Dale Minerals III
Equity Investments
Investments in affiliate	27,705	$ 28,672	$ 27,705	$ 28,672	$ 28,114	$ 28,529	$ 28,770	$ 28,974
Other Commitment									$ 30,000
Distributions received	$ 546	$ 648	$ 1,139	$ 1,176
All Dale Minerals III \| All Dale Minerals III
Equity Investments
Ownership percentage by limited partners			13.90%