Business Segments (Principal Geographical Areas) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Principal Geographical Areas Information
Revenue from external customers	$ 3,790,755	$ 4,641,830	$ 5,318,763
Total assets	4,542,800	4,724,898
Civil
Principal Geographical Areas Information
Revenue from external customers	$ 1,734,882	2,095,760	2,199,899
Civil, Building, and Specialty Contractors | Customer Concentration Risk | Revenue Benchmark
Principal Geographical Areas Information
Concentration risk, percentage	16.30%
United States
Principal Geographical Areas Information
Revenue from external customers	$ 3,424,574	4,267,734	4,953,045
Total assets	4,199,604	4,479,873
Foreign and U.S. territories
Principal Geographical Areas Information
Revenue from external customers	366,181	374,096	$ 365,718
Total assets	$ 343,196	$ 245,025