Property and Equipment - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 157,419	$ 161,273
Less accumulated depreciation	(97,955)	(93,146)
Total property and equipment, net	59,464	68,127
Construction equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	121,364	121,441
Transportation equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	18,275	19,017
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,547	12,771
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,339	3,108
Leasehold improvement
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	914	914
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,432	313
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,348	3,509
Water rights
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 200	$ 200

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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