Supplemental Balance Sheet Information - Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Supplemental Balance Sheet Data [Abstract]
Raw materials and supplies	$ 30,265	$ 31,399
Work-in-process	3,246	2,207
Finished products	13,596	14,015
Construction materials	16,862	16,332
Total	$ 63,969	$ 63,953

Supplemental Balance Sheet Data [Abstract]

No definition available.

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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

+ 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/presentationRef
-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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=68049868&loc=d3e3927-108312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765

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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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- Definition

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

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- Definition

Carrying amount as of the balance sheet date of unprocessed goods that will be used in the course of a construction project which will become a part of the finished inventory.

+ References

+ Details

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