| Goodwill by Operating Segment | 
Changes in goodwill for the six months ended June 30, 2019 are as follows (in thousands):
 
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   | 
   | 
Supply Chain Management  | 
   | 
Federal Services  | 
   | 
Aviation  | 
   | 
Total  | 
 
Balance as of December 31, 2018  | 
   | 
$  | 
63,190  | 
 
  | 
   | 
$  | 
30,883  | 
 
  | 
   | 
$  | 
104,549  | 
 
  | 
   | 
$  | 
198,622  | 
 
  | 
 
Increase from acquisition  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
60,590  | 
 
  | 
   | 
60,590  | 
 
  | 
 
Balance as of June 30, 2019  | 
   | 
$  | 
63,190  | 
 
  | 
   | 
$  | 
30,883  | 
 
  | 
   | 
$  | 
165,139  | 
 
  | 
   | 
$  | 
259,212  | 
 
  | 
 
  
 
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| Schedule of Intangible Assets | 
Intangible assets, net were comprised of the following (in thousands): 
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   | 
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Cost  | 
   | 
Accumulated Amortization  | 
   | 
 Accumulated 
Impairment Loss 
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   | 
Net Intangible Assets  | 
 
June 30, 2019  | 
   | 
   | 
   | 
   | 
   | 
   | 
   | 
   | 
 
Contract and customer-related  | 
   | 
$  | 
228,094  | 
 
  | 
   | 
$  | 
(94,185  | 
)  | 
   | 
$  | 
(1,025  | 
)  | 
   | 
$  | 
132,884  | 
 
  | 
 
Acquired technologies  | 
   | 
12,400  | 
 
  | 
   | 
(9,096  | 
)  | 
   | 
—  | 
 
  | 
   | 
3,304  | 
 
  | 
 
Trade names  | 
   | 
24,670  | 
 
  | 
   | 
(12,937  | 
)  | 
   | 
—  | 
 
  | 
   | 
11,733  | 
 
  | 
 
Total  | 
   | 
$  | 
265,164  | 
 
  | 
   | 
$  | 
(116,218  | 
)  | 
   | 
$  | 
(1,025  | 
)  | 
   | 
$  | 
147,921  | 
 
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   | 
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December 31, 2018  | 
   | 
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   | 
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   | 
   | 
 
  | 
   | 
   | 
 
  | 
 
Contract and customer-related  | 
   | 
$  | 
173,094  | 
 
  | 
   | 
$  | 
(86,076  | 
)  | 
   | 
$  | 
(1,025  | 
)  | 
   | 
$  | 
85,993  | 
 
  | 
 
Acquired technologies  | 
   | 
12,400  | 
 
  | 
   | 
(8,533  | 
)  | 
   | 
—  | 
 
  | 
   | 
3,867  | 
 
  | 
 
Trade names  | 
   | 
16,670  | 
 
  | 
   | 
(11,638  | 
)  | 
   | 
—  | 
 
  | 
   | 
5,032  | 
 
  | 
 
Total  | 
   | 
$  | 
202,164  | 
 
  | 
   | 
$  | 
(106,247  | 
)  | 
   | 
$  | 
(1,025  | 
)  | 
   | 
$  | 
94,892  | 
 
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