Inventories and natural gas in storage (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Inventory Disclosure [Abstract]
Aggregates held for resale	$ 195,489	$ 184,363	$ 180,450
Asphalt oil	93,816	57,002	59,853
Materials and supplies	35,967	30,629	26,481
Merchandise for resale	33,393	28,501	24,319
Natural gas in storage (current)	10,801	18,867	8,113
Other	10,850	16,247	17,521
Total	380,316	335,609	316,737
Natural gas in storage noncurrent	$ 47,500	$ 47,500	$ 47,500

Aggregated amount of aggregates held for resale. This amount is net of valuation reserves and adjustments.

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- Definition

Aggregated amount of asphalt oil inventory. This amount is net of valuation reserves and adjustments.

+ References

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- Definition

Carrying amount as of the balance sheet date of natural gas in storage, which is a mixture of gases (liquefied or otherwise), used for fuel and manufacturing purposes, which is ready for sale.

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Carrying amount as of the balance sheet date of natural gas stored underground in depleted gas reservoirs, aquifers, or salt caverns to meet future seasonal and peak load demands and also as insurance against unforeseen supply disruptions, and deemed to be a noncurrent asset because it is not expected to be used within 12 months or in the normal operating cycle.

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

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Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

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

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