Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date.

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- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

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Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands			3 Months Ended
	Apr. 10, 2017	Aug. 05, 2015	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition [Line Items]
Amortization expense			$ 847	$ 1,270
TAS Commercial Concrete
Business Acquisition [Line Items]
Amortization expense			$ 800
Business combination, indefinite-lived intangible assets		$ 6,900
TAS Commercial Concrete \| Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles acquired	$ 700	$ 18,100
Acquired finite-lived intangible assets, useful life	7 years	8 years