Goodwill and Intangible Assets - Future Amortization Expense of Finite-lived Intangible Assets (Details) (West Construction, Inc.)	3 Months Ended
Mar. 31, 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

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration