Acquisitions - Intangible Assets Acquired (Details) - Command Transportation, LLC
Jun. 01, 2015
USD ($)
Business Acquisition [Line Items]  
Value $ 125,400,000
Customer relationships  
Business Acquisition [Line Items]  
Value $ 97,200,000
Useful Life 17 years
Carrier relationships  
Business Acquisition [Line Items]  
Value $ 18,300,000
Useful Life 17 years
Trade names  
Business Acquisition [Line Items]  
Value $ 5,000,000
Useful Life 4 years
Noncompete agreements  
Business Acquisition [Line Items]  
Value $ 4,900,000
Noncompete agreements | Minimum  
Business Acquisition [Line Items]  
Useful Life 5 years
Noncompete agreements | Maximum  
Business Acquisition [Line Items]  
Useful Life 8 years