Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands		9 Months Ended
	Aug. 05, 2015	Sep. 30, 2016	Sep. 30, 2015
Business Acquisition [Line Items]
Amortization expense		$ 5,466	$ 1,733
TAS Commercial Concrete
Business Acquisition [Line Items]
Amortization expense		$ 5,500
Business combination, indefinite-lived intangible assets	$ 6,900
TAS Commercial Concrete | Contractual backlog
Business Acquisition [Line Items]
Finite-lived intangibles acquired	$ 8,700
Acquired finite-lived intangible assets, useful life	2 years
TAS Commercial Concrete | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles acquired	$ 18,100
Acquired finite-lived intangible assets, useful life	8 years