Inventories and natural gas in storage (Details 2) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory and natural gas in storage [Line Items]
Aggregates held for resale	$ 139,681	$ 115,268
Asphalt oil	54,741	30,360
Materials and supplies	23,611	18,650
Merchandise for resale	22,552	14,905
Natural gas in storage (current)	22,117	20,950
Other	24,607	26,450
Total	287,309	226,583
Natural gas in storage noncurrent	$ 48,500	$ 49,300

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

No definition available.

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- Definition

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

+ References

No definition available.

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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.

+ References

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- Definition

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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- Definition

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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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.

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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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- Definition

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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