Business Segment Information Business Segment Information - Narrative (Details) $ in Millions	Dec. 31, 2017 USD ($)
Minimum [Member] \| Large Project Construction [Member]
Segment Reporting Information [Line Items]
Total Contract Value	$ 75
Maximum [Member] \| Construction [Member]
Segment Reporting Information [Line Items]
Total Contract Value	$ 75

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