Business Acquisition - Narrative (Details) - USD ($) $ in Thousands			3 Months Ended		12 Months Ended
	Apr. 10, 2017	Aug. 05, 2015	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2015	Apr. 09, 2017
Business Acquisition [Line Items]
Federal statutory tax rate					35.00%	35.00%
Tony Bagliore Concrete, Inc. (TBC)
Business Acquisition [Line Items]
Payments to acquire businesses	$ 6,000
Contingent considerations			$ 2,000	$ 2,000
Contingent considerations, fair value							$ 456
Goodwill, net of working capital adjustment							$ 3,100
GLM Concrete Solutions, LLC
Business Acquisition [Line Items]
Issued and outstanding membership interest acquired		49.00%
TAS Commercial Concrete
Business Acquisition [Line Items]
Payments to acquire businesses		$ 112,000
Goodwill, net of working capital adjustment		32,600
Goodwill expected to be tax deductible		$ 32,600
Goodwill, tax basis, amortization period		15 years
Minimum | Tony Bagliore Concrete, Inc. (TBC)
Business Acquisition [Line Items]
Property and equipment useful life		3 years
Maximum | Tony Bagliore Concrete, Inc. (TBC)
Business Acquisition [Line Items]
Property and equipment useful life		15 years