Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 05, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Amortization expense		$ 4,418	$ 110
TAS Commercial Concrete
Finite-Lived Intangible Assets [Line Items]
Amortization expense		4,300
Business combination, indefinite-lived intangible assets	$ 6,900
TAS Commercial Concrete | Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles acquired	$ 18,100
Acquired finite-lived intangible assets, useful life	8 years
TAS Commercial Concrete | Contractual backlog
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles acquired	$ 8,700
Acquired finite-lived intangible assets, useful life	2 years
West Construction, Inc.
Finite-Lived Intangible Assets [Line Items]
Amortization expense		$ 87
West Construction, Inc. | Minimum
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, useful life				1 year
West Construction, Inc. | Maximum
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, useful life				3 years