| Disaggregation of Revenue | 
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| Table 4.1: Revenue by Contract Type |  
 | 
For the Three Months Ended | 
 | 
For the Six Months Ended | 
 
 | 
March 31, 2022 | 
 | 
March 31, 2021 | 
 | 
March 31, 2022 | 
 | 
March 31, 2021 | 
 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 
 | 
(dollars in thousands) | 
 
| Performance-based | 
$ | 
516,210  | 
 | 
 | 
43.9 % | 
 | 
$ | 
349,749  | 
 | 
 | 
36.4 % | 
 | 
$ | 
1,007,166  | 
 | 
 | 
43.3 % | 
 | 
$ | 
643,709  | 
 | 
 | 
33.8 % | 
 
| Cost-plus | 
322,823  | 
 | 
 | 
27.4 % | 
 | 
286,082  | 
 | 
 | 
29.8 % | 
 | 
662,904  | 
 | 
 | 
28.5 % | 
 | 
670,565  | 
 | 
 | 
35.2 % | 
 
| Fixed price | 
158,867  | 
 | 
 | 
13.5 % | 
 | 
146,344  | 
 | 
 | 
15.3 % | 
 | 
310,372  | 
 | 
 | 
13.3 % | 
 | 
267,121  | 
 | 
 | 
14.0 % | 
 
| Time and materials | 
179,426  | 
 | 
 | 
15.2 % | 
 | 
177,105  | 
 | 
 | 
18.5 % | 
 | 
347,760  | 
 | 
 | 
14.9 % | 
 | 
323,439  | 
 | 
 | 
17.0 % | 
 
| Total revenue | 
$ | 
1,177,326  | 
 | 
 | 
 | 
 | 
$ | 
959,280  | 
 | 
 | 
 | 
 | 
$ | 
2,328,202  | 
 | 
 | 
 | 
 | 
$ | 
1,904,834  | 
 | 
 | 
 | 
 
  
 | 
 | 
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 | 
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 | 
 | 
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 | 
 | 
 | 
 | 
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 | 
 | 
 
| Table 4.2: Revenue by Customer Type |  
 | 
For the Three Months Ended | 
 | 
For the Six Months Ended | 
 
 | 
March 31, 2022 | 
 | 
March 31, 2021 | 
 | 
March 31, 2022 | 
 | 
March 31, 2021 | 
 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 
 | 
(dollars in thousands) | 
 
| U.S. state government agencies | 
$ | 
411,287  | 
 | 
 | 
35.0 % | 
 | 
$ | 
445,697  | 
 | 
 | 
46.5 % | 
 | 
$ | 
782,834  | 
 | 
 | 
33.7 % | 
 | 
$ | 
833,811  | 
 | 
 | 
43.8 % | 
 
| U.S. federal government agencies | 
553,707  | 
 | 
 | 
47.0 % | 
 | 
307,870  | 
 | 
 | 
32.1 % | 
 | 
1,117,801  | 
 | 
 | 
48.0 % | 
 | 
693,442  | 
 | 
 | 
36.4 % | 
 
| International government agencies | 
194,800  | 
 | 
 | 
16.5 % | 
 | 
171,700  | 
 | 
 | 
17.9 % | 
 | 
366,175  | 
 | 
 | 
15.7 % | 
 | 
319,042  | 
 | 
 | 
16.7 % | 
 
| Other, including local municipalities and commercial customers | 
17,532  | 
 | 
 | 
1.5 % | 
 | 
34,013  | 
 | 
 | 
3.5 % | 
 | 
61,392  | 
 | 
 | 
2.6 % | 
 | 
58,539  | 
 | 
 | 
3.1 % | 
 
| Total revenue | 
$ | 
1,177,326  | 
 | 
 | 
 | 
 | 
$ | 
959,280  | 
 | 
 | 
 | 
 | 
$ | 
2,328,202  | 
 | 
 | 
 | 
 | 
$ | 
1,904,834  | 
 | 
 | 
 | 
 
  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
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 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
| Table 4.3: Revenue by Geography |  
 | 
For the Three Months Ended | 
 | 
For the Six Months Ended | 
 
 | 
March 31, 2022 | 
 | 
March 31, 2021 | 
 | 
March 31, 2022 | 
 | 
March 31, 2021 | 
 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 | 
Amount | 
 | 
% | 
 
 | 
(dollars in thousands) | 
 
| United States | 
$ | 
971,365  | 
 | 
 | 
82.5 % | 
 | 
$ | 
778,350  | 
 | 
 | 
81.1 % | 
 | 
$ | 
1,939,653  | 
 | 
 | 
83.3 % | 
 | 
$ | 
1,568,529  | 
 | 
 | 
82.3 % | 
 
| United Kingdom | 
107,898  | 
 | 
 | 
9.1 % | 
 | 
72,882  | 
 | 
 | 
7.6 % | 
 | 
193,705  | 
 | 
 | 
8.3 % | 
 | 
137,668  | 
 | 
 | 
7.2 % | 
 
| Australia | 
46,670  | 
 | 
 | 
4.0 % | 
 | 
70,947  | 
 | 
 | 
7.4 % | 
 | 
99,484  | 
 | 
 | 
4.3 % | 
 | 
126,878  | 
 | 
 | 
6.7 % | 
 
| Rest of world | 
51,393  | 
 | 
 | 
4.4 % | 
 | 
37,101  | 
 | 
 | 
3.9 % | 
 | 
95,360  | 
 | 
 | 
4.1 % | 
 | 
71,759  | 
 | 
 | 
3.8 % | 
 
| Total revenue | 
$ | 
1,177,326  | 
 | 
 | 
 | 
 | 
$ | 
959,280  | 
 | 
 | 
 | 
 | 
$ | 
2,328,202  | 
 | 
 | 
 | 
 | 
$ | 
1,904,834  | 
 | 
 | 
 | 
 
  
 |