Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Inventories
Coal	$ 128,919	$ 96,954
Repair parts and supplies	142,236	126,061
Inventories	271,155	223,015
Allowance for slow-moving and obsolete inventories	$ 2,600	$ 2,400

Carrying amount as of the balance sheet date of coal, which is a combustible rock or minerals which are extracted from the ground and used as fuel.

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Period Type:	instant

- References

No definition available.

+ Details

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- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6))
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
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-Section 55
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-URI https://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

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- Definition

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date for elements of machinery or equipment held for the purpose of replacing similar parts in the course of repair or maintenance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.BB)
-URI https://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(a))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Amount of valuation reserve for inventory.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6))
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

+ Details

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