v3.25.2
Revenue Recognition - Disaggregation of Revenue (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Disaggregation Of Revenue [Line Items]        
Revenue from clients $ 476,155 $ 512,029 $ 963,773 $ 1,006,465
Time-and-Materials        
Disaggregation Of Revenue [Line Items]        
Revenue from clients 206,553 217,640 415,599 423,793
Fixed-Price        
Disaggregation Of Revenue [Line Items]        
Revenue from clients 238,239 235,344 476,306 460,140
Cost-Based        
Disaggregation Of Revenue [Line Items]        
Revenue from clients 31,363 59,045 71,868 122,532
U.S. Federal Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients 204,680 273,471 444,305 547,666
U.S. State and Local Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients 85,650 84,786 162,492 161,739
International Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients 29,260 28,696 56,336 53,959
Total Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients 319,590 386,953 663,133 763,364
Commercial        
Disaggregation Of Revenue [Line Items]        
Revenue from clients $ 156,565 $ 125,076 $ 300,640 $ 243,101
Customer Concentration Risk | Revenue from Contract with Customer        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 100.00% 100.00% 100.00% 100.00%
Customer Concentration Risk | Revenue from Contract with Customer | Time-and-Materials        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 43.00% 43.00% 43.00% 42.00%
Customer Concentration Risk | Revenue from Contract with Customer | Fixed-Price        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 50.00% 46.00% 49.00% 46.00%
Customer Concentration Risk | Revenue from Contract with Customer | Cost-Based        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 7.00% 11.00% 8.00% 12.00%
Customer Concentration Risk | Revenue from Contract with Customer | U.S. Federal Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 43.00% 53.00% 46.00% 55.00%
Customer Concentration Risk | Revenue from Contract with Customer | U.S. State and Local Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 18.00% 17.00% 17.00% 16.00%
Customer Concentration Risk | Revenue from Contract with Customer | International Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 6.00% 6.00% 6.00% 5.00%
Customer Concentration Risk | Revenue from Contract with Customer | Total Government        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 67.00% 76.00% 69.00% 76.00%
Customer Concentration Risk | Revenue from Contract with Customer | Commercial        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 33.00% 24.00% 31.00% 24.00%
Energy, Environment, Infrastructure, and Disaster Recovery        
Disaggregation Of Revenue [Line Items]        
Revenue from clients $ 248,004 $ 232,763 $ 486,700 $ 457,572
Energy, Environment, Infrastructure, and Disaster Recovery | Customer Concentration Risk | Revenue from Contract with Customer        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 52.00% 46.00% 51.00% 46.00%
Health and Social Programs        
Disaggregation Of Revenue [Line Items]        
Revenue from clients $ 159,068 $ 196,164 $ 327,966 $ 386,939
Health and Social Programs | Customer Concentration Risk | Revenue from Contract with Customer        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 33.00% 38.00% 34.00% 38.00%
Security and Other Civilian & Commercial        
Disaggregation Of Revenue [Line Items]        
Revenue from clients $ 69,083 $ 83,102 $ 149,107 $ 161,954
Security and Other Civilian & Commercial | Customer Concentration Risk | Revenue from Contract with Customer        
Disaggregation Of Revenue [Line Items]        
Revenue from clients, Percent 15.00% 16.00% 15.00% 16.00%