Goodwill and Intangible Assets - Future Amortization Expense of Finite-lived Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended
Oct. 31, 2012	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Amortization expense, expected to be recorded in 2015		$ 87
West Construction, Inc. \| Minimum
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets useful life	1 year
West Construction, Inc. \| Maximum
Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets useful life	3 years

Amount of amortization expense expected to be recognized during the next fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant