Goodwill and Intangible Assets - Future Amortization Expense of Finite-lived Intangible Assets (Details) - West Construction, Inc.	6 Months Ended
Jun. 30, 2015
Minimum
Indefinite-lived Intangible Assets [Line Items]
Acquired intangible assets useful life	1 year
Maximum
Indefinite-lived Intangible Assets [Line Items]
Acquired intangible assets useful life	3 years

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.

No definition available.

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration