v3.7.0.1
Business Combination (Details) - USD ($)
$ in Thousands
1 Months Ended 3 Months Ended
Feb. 28, 2017
Mar. 31, 2017
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Business Acquisition [Line Items]          
Note payable, carrying value   $ 145,291 $ 145,291   $ 100,686
Liabilities:          
Operating revenues     253,001 $ 228,024  
Net income     $ 40,754 $ 32,882  
UniRush, LLC [Member]          
Business Combination, Consideration Transferred [Abstract]          
Cash, including proceeds from notes payable $ 139,917        
Fair value of contingent consideration 18,000        
Total consideration 157,917        
Contingent consideration, earn-out payable $ 20,000        
Contingent consideration, earn-out period 5 years        
Assets:          
Cash and cash equivalents $ 656        
Accounts receivable, net 5,745        
Prepaid expenses and other assets 5,147        
Property and equipment, net 4,399        
Intangible assets 69,000        
Goodwill 87,306        
Total assets: 172,253        
Liabilities:          
Accounts payable 11,110        
Other liabilities 3,226        
Total liabilities: 14,336        
Net assets acquired 157,917        
Operating revenues   $ 11,900      
Subordinated Debt [Member] | UniRush, LLC [Member]          
Business Acquisition [Line Items]          
Cash raised from debt 20,000        
Term Facility [Member] | Line of Credit [Member] | UniRush, LLC [Member]          
Business Acquisition [Line Items]          
Note payable, carrying value 95,000        
Customer Relationships [Member] | UniRush, LLC [Member]          
Liabilities:          
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles 58,500        
Trade Names [Member] | UniRush, LLC [Member]          
Liabilities:          
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles $ 5,500        
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life     15 years    
Minimum [Member] | Customer Relationships [Member] | UniRush, LLC [Member]          
Liabilities:          
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life     5 years    
Maximum [Member] | Customer Relationships [Member] | UniRush, LLC [Member]          
Liabilities:          
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life     10 years