v3.26.1
Segment Information (Details)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Company
Jun. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Segment Reporting [Line Items]          
Number of operating subsidiaries | Company     100    
Revenues from unrelated entities $ 5,154,892 $ 4,304,400 $ 9,783,125 $ 8,171,772  
Total revenues 5,154,892 4,304,400 9,783,125 8,171,772  
Operating income (loss) 547,340 415,212 951,185 733,968  
Net periodic pension income 0 55 0 109  
Interest income (expense), net 4,322 (3,240) 10,549 2,147  
Income before income taxes 551,662 412,027 961,734 736,224  
Cost of sales 4,132,513 3,470,629 7,896,796 6,615,283  
Selling, general and administrative expenses 475,039 418,559 935,144 822,521  
Depreciation and amortization of property, plant, and equipment 19,391 16,557 37,753 32,139  
Amortization of identifiable intangible assets 34,871 30,089 69,083 56,452  
Capital expenditures 31,148 28,043 59,860 54,174  
Total assets 10,157,082   $ 10,157,082   $ 9,291,399
Number of reportable segments not disclosed flag     true    
UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities 5,154,892 4,169,836 $ 9,783,125 7,931,907  
Total revenues 5,154,892 4,169,836 9,783,125 7,931,907  
Operating income (loss) 591,030 446,007 1,040,383 811,994  
Cost of sales 4,132,513 3,352,640 7,896,796 6,404,197  
Selling, general and administrative expenses 431,349 371,189 845,946 715,716  
Depreciation and amortization of property, plant, and equipment 18,990 15,161 36,952 29,562  
Capital expenditures 30,430 24,545 57,672 46,794  
Total assets 8,934,677   8,934,677   7,855,266
United States Electrical Construction And Facilities Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities 1,662,501 1,340,247 3,109,915 2,428,091  
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities 2,300,873 1,755,258 4,327,214 3,327,860  
United States Building Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities 837,706 793,259 1,610,355 1,535,882  
United States Industrial Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities 353,812 281,072 735,641 640,074  
United Kingdom Building Services [Member] | UNITED KINGDOM          
Segment Reporting [Line Items]          
Revenues from unrelated entities 0 134,564 0 239,865  
Operating Segments [Member] | United States Electrical Construction And Facilities Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities 1,663,380 1,341,883 3,111,230 2,431,833  
Total revenues 1,667,015 1,364,158 3,116,437 2,478,353  
Operating income (loss) 231,417 157,644 405,898 293,701  
Cost of sales 1,307,721 1,080,188 2,473,484 1,956,431  
Selling, general and administrative expenses 123,363 102,415 230,533 177,959  
Depreciation and amortization of property, plant, and equipment 3,549 2,464 6,653 4,769  
Amortization of identifiable intangible assets 14,402 12,950 27,992 22,430  
Capital expenditures 6,517 4,187 13,677 8,809  
Total assets 3,047,655   3,047,655   2,686,933
Operating Segments [Member] | United States Mechanical Construction And Facilities Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities 2,308,799 1,756,632 4,340,316 3,330,253  
Total revenues 2,357,907 1,779,871 4,408,664 3,364,985  
Operating income (loss) 286,639 238,737 508,282 425,484  
Cost of sales 1,856,114 1,395,519 3,505,032 2,661,229  
Selling, general and administrative expenses 158,120 121,002 313,900 241,147  
Depreciation and amortization of property, plant, and equipment 7,904 5,365 15,393 10,241  
Amortization of identifiable intangible assets 9,459 5,978 18,918 11,375  
Capital expenditures 17,377 12,367 31,608 23,346  
Total assets 3,794,196   3,794,196   3,206,671
Operating Segments [Member] | United States Building Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Total revenues 852,694 805,703 1,636,248 1,557,587  
Operating income (loss) 63,375 50,045 103,824 86,468  
Cost of sales 664,295 634,690 1,283,355 1,236,199  
Selling, general and administrative expenses 110,036 108,524 223,176 213,215  
Depreciation and amortization of property, plant, and equipment 3,853 4,042 7,744 8,083  
Amortization of identifiable intangible assets 5,108 5,240 10,350 10,805  
Capital expenditures 3,173 4,770 5,562 8,113  
Total assets 1,509,928   1,509,928   1,436,779
Operating Segments [Member] | United States Industrial Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Total revenues 354,135 287,411 736,218 651,743  
Operating income (loss) 9,599 (419) 22,379 6,341  
Cost of sales 304,383 242,243 634,925 550,338  
Selling, general and administrative expenses 39,830 39,248 78,337 83,395  
Depreciation and amortization of property, plant, and equipment 3,684 3,290 7,162 6,469  
Amortization of identifiable intangible assets 5,902 5,921 11,823 11,842  
Capital expenditures 3,363 3,221 6,825 6,526  
Total assets 582,898   582,898   524,883
Operating Segments [Member] | United Kingdom Building Services [Member] | UNITED KINGDOM          
Segment Reporting [Line Items]          
Total revenues 0 134,564 0 239,865  
Operating income (loss) 0 8,425 0 13,412  
Cost of sales 0 117,989 0 211,086  
Selling, general and administrative expenses 0 8,150 0 15,367  
Depreciation and amortization of property, plant, and equipment 0 1,068 0 2,000  
Capital expenditures 0 1,928 0 4,384  
Corporate, Non-Segment [Member]          
Segment Reporting [Line Items]          
Operating income (loss) (43,690) (39,220) (89,198) (91,438)  
Selling, general and administrative expenses 43,690 39,220 89,198 91,438  
Depreciation and amortization of property, plant, and equipment 401 328 801 577  
Capital expenditures 718 1,570 2,188 2,996  
Total assets 1,222,405   1,222,405   $ 1,436,133
Intersegment Eliminations [Member]          
Segment Reporting [Line Items]          
Total revenues (76,859) (67,307) (114,442) (120,761)  
Intersegment Eliminations [Member] | United States Electrical Construction And Facilities Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities (879) (1,636) (1,315) (3,742)  
Intersegment Eliminations [Member] | United States Mechanical Construction And Facilities Services [Member] | UNITED STATES          
Segment Reporting [Line Items]          
Revenues from unrelated entities $ (7,926) $ (1,374) $ (13,102) $ (2,393)