SEGMENT REPORTING - Summary of Revenue from External Customers by Geographic Areas, by Customer and by Contract Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Segment Reporting [Line Items]
Revenue	$ 584,347	$ 313,925	$ 1,072,376	$ 548,140
Operating Segments
Segment Reporting [Line Items]
Revenue	584,347	313,925	1,072,376	548,140
Operating Segments \| Cost-reimbursable contracts
Segment Reporting [Line Items]
Revenue	539,785	300,777	998,900	521,549
Operating Segments \| Fixed-unit price contracts
Segment Reporting [Line Items]
Revenue	44,562	13,148	73,476	26,591
Operating Segments \| Public and quasi-public sector
Segment Reporting [Line Items]
Revenue	176,026	10,537	327,801	16,440
Operating Segments \| Private sector
Segment Reporting [Line Items]
Revenue	408,321	303,388	744,575	531,700
Operating Segments \| Inspection & Mitigation
Segment Reporting [Line Items]
Revenue	296,696	313,925	531,522	548,140
Operating Segments \| Inspection & Mitigation \| Cost-reimbursable contracts
Segment Reporting [Line Items]
Revenue	281,572	300,777	506,097	521,549
Operating Segments \| Inspection & Mitigation \| Fixed-unit price contracts
Segment Reporting [Line Items]
Revenue	15,124	13,148	25,425	26,591
Operating Segments \| Inspection & Mitigation \| Public and quasi-public sector
Segment Reporting [Line Items]
Revenue	11,123	10,537	17,999	16,440
Operating Segments \| Inspection & Mitigation \| Private sector
Segment Reporting [Line Items]
Revenue	285,573	303,388	513,523	531,700
Operating Segments \| Consulting & Engineering
Segment Reporting [Line Items]
Revenue	206,636	0	394,012	0
Operating Segments \| Consulting & Engineering \| Cost-reimbursable contracts
Segment Reporting [Line Items]
Revenue	179,009	0	349,355	0
Operating Segments \| Consulting & Engineering \| Fixed-unit price contracts
Segment Reporting [Line Items]
Revenue	27,627	0	44,657	0
Operating Segments \| Consulting & Engineering \| Public and quasi-public sector
Segment Reporting [Line Items]
Revenue	98,177	0	187,682	0
Operating Segments \| Consulting & Engineering \| Private sector
Segment Reporting [Line Items]
Revenue	108,459	0	206,330	0
Operating Segments \| Geospatial
Segment Reporting [Line Items]
Revenue	81,015	0	146,842	0
Operating Segments \| Geospatial \| Cost-reimbursable contracts
Segment Reporting [Line Items]
Revenue	79,204	0	143,448	0
Operating Segments \| Geospatial \| Fixed-unit price contracts
Segment Reporting [Line Items]
Revenue	1,811	0	3,394	0
Operating Segments \| Geospatial \| Public and quasi-public sector
Segment Reporting [Line Items]
Revenue	66,726	0	122,120	0
Operating Segments \| Geospatial \| Private sector
Segment Reporting [Line Items]
Revenue	14,289	0	24,722	0
Operating Segments \| United States
Segment Reporting [Line Items]
Revenue	404,557	161,308	757,302	306,629
Operating Segments \| United States \| Inspection & Mitigation
Segment Reporting [Line Items]
Revenue	154,421	161,308	288,464	306,629
Operating Segments \| United States \| Consulting & Engineering
Segment Reporting [Line Items]
Revenue	173,151	0	329,471	0
Operating Segments \| United States \| Geospatial
Segment Reporting [Line Items]
Revenue	76,985	0	139,367	0
Operating Segments \| Canada
Segment Reporting [Line Items]
Revenue	140,044	149,954	238,285	236,482
Operating Segments \| Canada \| Inspection & Mitigation
Segment Reporting [Line Items]
Revenue	139,552	149,954	237,565	236,482
Operating Segments \| Canada \| Consulting & Engineering
Segment Reporting [Line Items]
Revenue	0	0	0	0
Operating Segments \| Canada \| Geospatial
Segment Reporting [Line Items]
Revenue	492	0	720	0
Operating Segments \| Other foreign
Segment Reporting [Line Items]
Revenue	39,746	2,663	76,789	5,029
Operating Segments \| Other foreign \| Inspection & Mitigation
Segment Reporting [Line Items]
Revenue	2,723	2,663	5,493	5,029
Operating Segments \| Other foreign \| Consulting & Engineering
Segment Reporting [Line Items]
Revenue	33,485	0	64,541	0
Operating Segments \| Other foreign \| Geospatial
Segment Reporting [Line Items]
Revenue	$ 3,538	$ 0	$ 6,755	$ 0