Fair Value Measurement (Details) (USD $)
9 Months Ended
Sep. 30, 2012
Contingent consideration
Sep. 30, 2012
Minimum
Sep. 30, 2012
Maximum
Sep. 30, 2012
Level 3
Sep. 30, 2012
Level 3
Contingent consideration
Sep. 30, 2011
Level 3
Contingent consideration
Sep. 30, 2012
Level 3
RGA
Contingent consideration
Sep. 30, 2011
Level 3
RGA
Contingent consideration
Sep. 30, 2012
Level 3
DSI
Contingent consideration
Sep. 30, 2012
Level 3
Nationwide Traffic Services, LLC.
Contingent consideration
Sep. 30, 2012
Level 3
Lubenow
Contingent consideration
Sep. 30, 2011
Level 3
Lubenow
Contingent consideration
Sep. 30, 2012
Level 3
Freight Management, Inc. [Member]
Contingent consideration
Sep. 30, 2011
Level 3
Freight Management, Inc. [Member]
Contingent consideration
Sep. 30, 2012
Level 3
Advantage Transport, Inc. [Member]
Contingent consideration
Sep. 30, 2012
Level 3
Selling, general and administrative expenses
Sep. 30, 2011
Level 3
Selling, general and administrative expenses
Sep. 30, 2012
Fair Value, Measurements, Recurring
Total
Contingent consideration
Dec. 31, 2011
Fair Value, Measurements, Recurring
Total
Contingent consideration
Sep. 30, 2012
Fair Value, Measurements, Recurring
Level 1
Contingent consideration
Dec. 31, 2011
Fair Value, Measurements, Recurring
Level 1
Contingent consideration
Sep. 30, 2012
Fair Value, Measurements, Recurring
Level 2
Contingent consideration
Dec. 31, 2011
Fair Value, Measurements, Recurring
Level 2
Contingent consideration
Sep. 30, 2012
Fair Value, Measurements, Recurring
Level 3
Contingent consideration
Dec. 31, 2011
Fair Value, Measurements, Recurring
Level 3
Contingent consideration
Sep. 30, 2012
Fair Value, Measurements, Recurring
Money market funds
Total
Dec. 31, 2011
Fair Value, Measurements, Recurring
Money market funds
Total
Sep. 30, 2012
Fair Value, Measurements, Recurring
Money market funds
Level 1
Dec. 31, 2011
Fair Value, Measurements, Recurring
Money market funds
Level 1
Sep. 30, 2012
Fair Value, Measurements, Recurring
Money market funds
Level 2
Dec. 31, 2011
Fair Value, Measurements, Recurring
Money market funds
Level 2
Sep. 30, 2012
Fair Value, Measurements, Recurring
Money market funds
Level 3
Dec. 31, 2011
Fair Value, Measurements, Recurring
Money market funds
Level 3
Fair value measurement:                                                                  
Probability rate of paying the contingent consideration   5.00% 55.00%                                                            
Discount rate used to determine fair value of contingent consideration   6.00% 12.00%                                                            
Assets:                                                                  
Money market funds                                                   $ 0 $ 5,048,029 $ 0 $ 5,048,029 $ 0 $ 0 $ 0 $ 0
Liabilities:                                                                  
Contingent consideration obligation 10,158,175                                 10,158,175 12,852,281 0 0 0 0 10,158,175 12,852,281                
Reconciliation of the beginning and ending balances of the liabilities measured at fair value                                                                  
Balance at beginning of period       (12,852,281)                                                          
Increase related to purchase accounting for acquisitions       (631,914)                                                          
Change in fair value       443,520                       443,520 246,737                                
Payment of contingent consideration       2,882,500 2,882,500 1,000,000 200,000 200,000 520,000 437,500 280,000 280,000 520,000 520,000 925,000                                    
Balance at end of period       $ (10,158,175)