Amount of cash outflow in the form of cash settlement of grants under deferred compensation plan.

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Amount of partnership capital allocated for share-based obligations.

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Amount of reduction in share based compensation expense as a result of modified awards.

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No definition available.

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Reversal of cumulative previously recognized expenses.

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No definition available.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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COMMON UNIT-BASED COMPENSATION PLANS - LTIP Other Information (Details) - USD ($) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other information
Cash settlement of grants	$ 2,490
ARLP LTIP
Other information
Unit-based compensation expense	8,100	$ 10,400	$ 10,800
Reduction in compensation expense	1,000
Total unit-based obligation recorded	1,300	$ 20,200
Unrecognized compensation expense (in dollars)	$ 5,800
Weighted-average period for recognition of expense	2 years
Units available for grant	1.7
2018 Grants \| ARLP LTIP
Other information
Incremental compensation cost	$ 5,400
2019 Grants \| ARLP LTIP
Other information
Reversal of cumulative previously recognized expenses	$ 4,800