Number of monthly payments.

No definition available.

Name:	arlp_NumberOfMonthlyPayments
Namespace Prefix:	arlp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments including both interest and principal payments.

+ References

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+ Details

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

- Definition

Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

+ References

No definition available.

+ Details

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=arlp_MayTwoThousandNineteenEquipmentFinancingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=arlp_NovemberTwoThousandNineteenEquipmentFinancingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=arlp_EquipmentFinancingJune2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LONG-TERM DEBT - Equipment financing and other (Details) $ in Millions	Jun. 05, 2020 USD ($)	Nov. 06, 2019 USD ($) payment	May 17, 2019 USD ($)
May 2019 Equipment Financing
Long-Term Debt
Principal amount			$ 10.0
Term			36 months
Effective interest rate (as a percent)			6.25%
November 2019 Equipment Financing
Long-Term Debt
Principal amount		$ 53.1
Term		4 years
Effective interest rate (as a percent)		4.75%
Number of monthly payments \| payment		47
Periodic Payment		$ 1.0
Balloon payment on maturity		$ 11.6
June 2020 equipment financing
Long-Term Debt
Principal amount	$ 14.7
Term	48 months
Effective interest rate (as a percent)	6.10%