| Disaggregation of Revenue | 
A summary of revenues for our operating groups by customer for the three and six months ended June 30, 2019 are as follows (in thousands):
 
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Three months ended June 30, 2019  | 
 
Customer  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
USPS  | 
   | 
$  | 
42,112  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
42,112  | 
 
  | 
 
DoD  | 
   | 
6,461  | 
 
  | 
   | 
260  | 
 
  | 
   | 
68,359  | 
 
  | 
   | 
75,080  | 
 
  | 
 
Commercial  | 
   | 
5,090  | 
 
  | 
   | 
54,086  | 
 
  | 
   | 
—  | 
 
  | 
   | 
59,176  | 
 
  | 
 
Other government  | 
   | 
142  | 
 
  | 
   | 
651  | 
 
  | 
   | 
11,950  | 
 
  | 
   | 
12,743  | 
 
  | 
 
   | 
   | 
$  | 
53,805  | 
 
  | 
   | 
$  | 
54,997  | 
 
  | 
   | 
$  | 
80,309  | 
 
  | 
   | 
$  | 
189,111  | 
 
  | 
 
  
  
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Six months ended June 30, 2019  | 
 
Customer  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
USPS  | 
   | 
$  | 
84,795  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
84,795  | 
 
  | 
 
DoD  | 
   | 
11,303  | 
 
  | 
   | 
1,155  | 
 
  | 
   | 
125,323  | 
 
  | 
   | 
137,781  | 
 
  | 
 
Commercial  | 
   | 
9,070  | 
 
  | 
   | 
102,561  | 
 
  | 
   | 
1,104  | 
 
  | 
   | 
112,735  | 
 
  | 
 
Other government  | 
   | 
341  | 
 
  | 
   | 
651  | 
 
  | 
   | 
22,727  | 
 
  | 
   | 
23,719  | 
 
  | 
 
   | 
   | 
$  | 
105,509  | 
 
  | 
   | 
$  | 
104,367  | 
 
  | 
   | 
$  | 
149,154  | 
 
  | 
   | 
$  | 
359,030  | 
 
  | 
 
  
  
A summary of revenues for our operating groups by customer for the three and six months ended June 30, 2018 are as follows (in thousands): 
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Three months ended June 30, 2018  | 
 
Customer  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
USPS  | 
   | 
$  | 
43,089  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
43,089  | 
 
  | 
 
DoD  | 
   | 
7,525  | 
 
  | 
   | 
1,025  | 
 
  | 
   | 
73,637  | 
 
  | 
   | 
82,187  | 
 
  | 
 
Commercial  | 
   | 
3,413  | 
 
  | 
   | 
34,037  | 
 
  | 
   | 
31  | 
 
  | 
   | 
37,481  | 
 
  | 
 
Other government  | 
   | 
236  | 
 
  | 
   | 
742  | 
 
  | 
   | 
6,659  | 
 
  | 
   | 
7,637  | 
 
  | 
 
   | 
   | 
$  | 
54,263  | 
 
  | 
   | 
$  | 
35,804  | 
 
  | 
   | 
$  | 
80,327  | 
 
  | 
   | 
$  | 
170,394  | 
 
  | 
 
  
  
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Six months ended June 30, 2018  | 
 
Customer  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
USPS  | 
   | 
$  | 
87,120  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
87,120  | 
 
  | 
 
DoD  | 
   | 
15,701  | 
 
  | 
   | 
2,240  | 
 
  | 
   | 
151,899  | 
 
  | 
   | 
169,840  | 
 
  | 
 
Commercial  | 
   | 
6,799  | 
 
  | 
   | 
65,572  | 
 
  | 
   | 
233  | 
 
  | 
   | 
72,604  | 
 
  | 
 
Other government  | 
   | 
507  | 
 
  | 
   | 
742  | 
 
  | 
   | 
16,478  | 
 
  | 
   | 
17,727  | 
 
  | 
 
   | 
   | 
$  | 
110,127  | 
 
  | 
   | 
$  | 
68,554  | 
 
  | 
   | 
$  | 
168,610  | 
 
  | 
   | 
$  | 
347,291  | 
 
  | 
 
  
  
  
A summary of revenues for our operating groups by contract type for the three and six months ended June 30, 2019 are as follows (in thousands):
 
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Three months ended June 30, 2019  | 
 
Contract Type  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
Cost-type  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
169  | 
 
  | 
   | 
$  | 
33,496  | 
 
  | 
   | 
$  | 
33,665  | 
 
  | 
 
Fixed-price  | 
   | 
53,805  | 
 
  | 
   | 
25,056  | 
 
  | 
   | 
19,153  | 
 
  | 
   | 
98,014  | 
 
  | 
 
Time and materials  | 
   | 
—  | 
 
  | 
   | 
29,772  | 
 
  | 
   | 
27,660  | 
 
  | 
   | 
57,432  | 
 
  | 
 
Total revenues  | 
   | 
$  | 
53,805  | 
 
  | 
   | 
$  | 
54,997  | 
 
  | 
   | 
$  | 
80,309  | 
 
  | 
   | 
$  | 
189,111  | 
 
  | 
 
  
  
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Six months ended June 30, 2019  | 
 
Contract Type  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
Cost-type  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
381  | 
 
  | 
   | 
$  | 
61,336  | 
 
  | 
   | 
$  | 
61,717  | 
 
  | 
 
Fixed-price  | 
   | 
105,509  | 
 
  | 
   | 
48,992  | 
 
  | 
   | 
39,020  | 
 
  | 
   | 
193,521  | 
 
  | 
 
Time and materials  | 
   | 
—  | 
 
  | 
   | 
54,994  | 
 
  | 
   | 
48,798  | 
 
  | 
   | 
103,792  | 
 
  | 
 
Total revenues  | 
   | 
$  | 
105,509  | 
 
  | 
   | 
$  | 
104,367  | 
 
  | 
   | 
$  | 
149,154  | 
 
  | 
   | 
$  | 
359,030  | 
 
  | 
 
  
  
A summary of revenues for our operating groups by contract type for the three and six months ended June 30, 2018 are as follows (in thousands): 
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Three months ended June 30, 2018  | 
 
Contract Type  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
Cost-type  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
701  | 
 
  | 
   | 
$  | 
41,801  | 
 
  | 
   | 
$  | 
42,502  | 
 
  | 
 
Fixed-price  | 
   | 
54,263  | 
 
  | 
   | 
19,869  | 
 
  | 
   | 
17,204  | 
 
  | 
   | 
91,336  | 
 
  | 
 
Time and materials  | 
   | 
—  | 
 
  | 
   | 
15,234  | 
 
  | 
   | 
21,322  | 
 
  | 
   | 
36,556  | 
 
  | 
 
Total revenues  | 
   | 
$  | 
54,263  | 
 
  | 
   | 
$  | 
35,804  | 
 
  | 
   | 
$  | 
80,327  | 
 
  | 
   | 
$  | 
170,394  | 
 
  | 
 
  
  
 |  
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
 
   | 
   | 
Six months ended June 30, 2018  | 
 
Contract Type  | 
   | 
Supply Chain Management  | 
   | 
Aviation  | 
   | 
Federal Services  | 
   | 
Total  | 
 
Cost-type  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
1,098  | 
 
  | 
   | 
$  | 
92,922  | 
 
  | 
   | 
$  | 
94,020  | 
 
  | 
 
Fixed-price  | 
   | 
110,127  | 
 
  | 
   | 
39,373  | 
 
  | 
   | 
32,343  | 
 
  | 
   | 
181,843  | 
 
  | 
 
Time and materials  | 
   | 
—  | 
 
  | 
   | 
28,083  | 
 
  | 
   | 
43,345  | 
 
  | 
   | 
71,428  | 
 
  | 
 
Total revenues  | 
   | 
$  | 
110,127  | 
 
  | 
   | 
$  | 
68,554  | 
 
  | 
   | 
$  | 
168,610  | 
 
  | 
   | 
$  | 
347,291  | 
 
  | 
 
  
 
 |