Revenue (Schedule Of Revenue By Contract Type) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 952,154	$ 1,207,595
Fixed price
Disaggregation of Revenue [Line Items]
Revenue	638,574	797,073
Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	177,135	272,854
Unit price
Disaggregation of Revenue [Line Items]
Revenue	65,365	81,141
Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	71,080	56,527
Civil
Disaggregation of Revenue [Line Items]
Revenue	390,795	475,575
Civil | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	336,993	419,156
Civil | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	293	1,270
Civil | Unit price
Disaggregation of Revenue [Line Items]
Revenue	50,510	52,733
Civil | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	2,999	2,416
Building
Disaggregation of Revenue [Line Items]
Revenue	330,648	407,233
Building | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	102,518	84,449
Building | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	171,509	270,454
Building | Unit price
Disaggregation of Revenue [Line Items]
Revenue	33	111
Building | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	56,588	52,219
Specialty Contractors
Disaggregation of Revenue [Line Items]
Revenue	230,711	324,787
Specialty Contractors | Fixed price
Disaggregation of Revenue [Line Items]
Revenue	199,063	293,468
Specialty Contractors | Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Revenue	5,333	1,130
Specialty Contractors | Unit price
Disaggregation of Revenue [Line Items]
Revenue	14,822	28,297
Specialty Contractors | Cost plus fee and other
Disaggregation of Revenue [Line Items]
Revenue	$ 11,493	$ 1,892