Business Segments (Total Assets For Reportable Segments) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Assets	$ 4,719,683	$ 4,724,898
Corporate and other
Segment Reporting Information [Line Items]
Assets	(232,724)	(198,449)
Civil | Operating Segments
Segment Reporting Information [Line Items]
Assets	3,432,649	3,310,648
Building | Operating Segments
Segment Reporting Information [Line Items]
Assets	919,426	980,989
Specialty Contractors | Operating Segments
Segment Reporting Information [Line Items]
Assets	$ 600,332	$ 631,710