Business Segments (Total Assets For Reportable Segments) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Assets	$ 4,792,158	$ 4,724,898
Corporate and other
Segment Reporting Information [Line Items]
Assets	(227,027)	(198,449)
Civil | Operating Segments
Segment Reporting Information [Line Items]
Assets	3,419,911	3,310,648
Building | Operating Segments
Segment Reporting Information [Line Items]
Assets	969,388	980,989
Specialty Contractors | Operating Segments
Segment Reporting Information [Line Items]
Assets	$ 629,886	$ 631,710