SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Intangible Assets
Amortization expense attributable to intangible assets	$ 1,200	$ 3,800	$ 4,900
Original Cost	12,123	12,123
Accumulated Amortization	(11,095)	(9,922)
Intangibles, Net	1,028	2,201
Estimated amortization expense attributable to intangible assets
2023	54
2024	54
2025	54
2026	54
2027	54
Thereafter	758
Customer contracts, net
Intangible Assets
Original Cost	10,623	10,623
Accumulated Amortization	(10,623)	(9,504)
Intangibles, Net		1,119
Permits
Intangible Assets
Original Cost	1,500	1,500
Accumulated Amortization	(472)	(418)
Intangibles, Net	$ 1,028	$ 1,082

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization for asset, excluding financial asset and goodwill, lacking physical substance with finite life expected to be recognized after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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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.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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