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Inventories and natural gas in storage (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018 | Jun. 30, 2018
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Inventory Disclosure [Abstract] |  |  |
Aggregates held for resale | $ 147,030 | $ 139,681 | $ 131,784
Asphalt oil | 80,418 | 54,741 | 64,560
Materials and supplies | 28,746 | 23,611 | 24,688
Merchandise for resale | 27,167 | 22,552 | 17,502
Natural gas in storage (current) | 15,841 | 22,117 | 13,774
Other | 26,742 | 24,607 | 25,931
Total | 325,944 | 287,309 | 278,239
Natural gas in storage noncurrent | $ 48,200 | $ 48,500 | $ 47,800

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- Definition Aggregated amount of asphalt oil inventory. This amount is net of valuation reserves and adjustments. + References No definition available. + Details
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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 Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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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. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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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. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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