| Goodwill and Intangible Assets (Tables)
 | 12 Months Ended | 
| Dec. 31, 2015 | 
|---|
| Goodwill and Intangible Assets [Abstract] |  | 
| Goodwill by Operating Segment | 
Changes in goodwill for the years ended December 31, 2015 and 2014 are as follows (in thousands): 
 
|  |  | Supply Chain Management |  |  | IT, Energy and Management Consulting |  |  | Aviation |  |  | Total |  |  
| Balance as of December 31, 2013 |  | $ | 61,169 |  |  | $ | 30,883 |  |  | $ | - |  |  | $ | 92,052 |  |  
| Balance as of December 31, 2014 |  | $ | 61,169 |  |  | $ | 30,883 |  |  | $ | - |  |  | $ | 92,052 |  |  
| Increase from acquisitions |  |  | 1,944 |  |  |  | - |  |  |  | 104,549 |  |  |  | 106,493 |  |  
| Balance as of December 31, 2015 |  | $ | 63,113 |  |  | $ | 30,883 |  |  | $ | 104,549 |  |  | $ | 198,545 |  |  | 
| Intangible Assets | 
Intangible assets were composed of the following (in thousands): 
 
|  |  | Cost |  |  | Accumulated Amortization |  |  | Accumulated Impairment Loss |  |  | Net Intangible Assets |  |  
| December 31, 2015 |  |  |  |  |  |  |  |  |  |  |  |  |  
| Contract and customer-related |  | $ | 173,084 |  |  | $ | (46,611 | ) |  | $ | (1,025 | ) |  | $ | 125,448 |  |  
| Acquired technologies |  |  | 12,400 |  |  |  | (5,151 | ) |  |  | - |  |  |  | 7,249 |  |  
| Trade names |  |  | 16,730 |  |  |  | (6,384 | ) |  |  | - |  |  |  | 10,346 |  |  
|     Total |  | $ | 202,214 |  |  | $ | (58,146 | ) |  | $ | (1,025 | ) |  | $ | 143,043 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| December 31, 2014 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Contract and customer-related |  | $ | 93,304 |  |  | $ | (33,840 | ) |  | $ | (1,025 | ) |  | $ | 58,439 |  |  
| Acquired technologies |  |  | 12,400 |  |  |  | (4,024 | ) |  |  | - |  |  |  | 8,376 |  |  
| Trade names |  |  | 10,100 |  |  |  | (4,706 | ) |  |  | - |  |  |  | 5,394 |  |  
|     Total |  | $ | 115,804 |  |  | $ | (42,570 | ) |  | $ | (1,025 | ) |  | $ | 72,209 |  |  | 
| Future Amortization of Intangible Assets | 
Future expected amortization of intangible assets is as follows for the years ending December 31, (in thousands): 
|  |  | Amortization |  |  
| 2016 |  | $ | 16,130 |  |  
| 2017 |  |  | 16,080 |  |  
| 2018 |  |  | 16,080 |  |  
| 2019 |  |  | 16,016 |  |  
| 2020 |  |  | 15,425 |  |  
| Thereafter |  |  | 63,312 |  |  
|   Total |  | $ | 143,043 |  |  |