Business Segments (Reconciliation of Segment Results to Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Total assets	$ 4,542,800	$ 4,724,898
Corporate, Non-Segment
Total assets	(242,485)	(198,449)
Civil | Operating Segments
Total assets	3,402,934	3,310,648
Building | Operating Segments
Total assets	898,816	980,989
Specialty Contractors | Operating Segments
Total assets	$ 483,535	$ 631,710