Quarterly report pursuant to Section 13 or 15(d)

Recent Accounting Pronouncements (Details)

v3.10.0.1
Recent Accounting Pronouncements (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2018
USD ($)
$ / shares
Jun. 30, 2017
USD ($)
$ / shares
Jun. 30, 2018
USD ($)
$ / shares
Jun. 30, 2017
USD ($)
$ / shares
Dec. 31, 2017
USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Accounts Receivable, Net, Current $ 152,393   $ 152,393   $ 147,948
Number of principal reporting segments     4    
Operating revenue 330,343 $ 283,876 $ 632,951 $ 545,921  
Operating Income (Loss) 32,870 29,996 57,105 53,738  
Income Tax Expense (Benefit) 8,088 10,112 14,212 18,966  
Net income $ 24,298 $ 19,666 $ 42,038 $ 34,246  
Diluted (in dollars per share) | $ / shares $ 0.82 $ 0.65 $ 1.42 $ 1.13  
Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   $ 283,876   $ 545,921  
Operating Expenses   253,880   492,183  
Operating Income (Loss)   29,996   53,738  
Income Tax Expense (Benefit)   10,112   18,966  
Net income   $ 19,666   $ 34,246  
Diluted (in dollars per share) | $ / shares   $ 0.65   $ 1.13  
Accounting Standards Update 2014-09 [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification   $ 15,392   $ 29,595  
Expedited LTL [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue $ 191,159 159,842 $ 359,521 308,021  
Operating Income (Loss) 26,526 23,047 47,298 41,975  
Expedited LTL [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   160,472   309,237  
Truckload Premium Services [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   50,451   97,538  
Pool Distribution [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue 43,197 37,685 85,804 76,416  
Operating Income (Loss) 1,589 1,625 2,960 2,991  
Pool Distribution [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   37,756   76,558  
Intermodal [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue 49,084 37,220 97,562 66,116  
Operating Income (Loss) 5,543 3,209 9,012 5,763  
Intermodal [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   37,240   66,147  
Elimination [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating Income (Loss) $ (2,505) 260 $ (3,839) (601)  
Elimination [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   (2,043)   (3,559)  
Scenario, Previously Reported [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   267,518   514,499  
Operating Expenses   237,709   461,502  
Operating Income (Loss)   29,809   52,997  
Income Tax Expense (Benefit)   10,041   18,678  
Net income   $ 19,550   $ 33,793  
Diluted (in dollars per share) | $ / shares   $ 0.64   $ 1.11  
Scenario, Previously Reported [Member] | Expedited LTL [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   $ 152,270   $ 292,868  
Scenario, Previously Reported [Member] | Truckload Premium Services [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   45,186   86,971  
Scenario, Previously Reported [Member] | Pool Distribution [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   36,835   74,658  
Scenario, Previously Reported [Member] | Intermodal [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   35,270   63,561  
Scenario, Previously Reported [Member] | Elimination [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   (2,043)   (3,559)  
Restatement Adjustment [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   16,358   31,422  
Operating Expenses   16,171   30,681  
Operating Income (Loss)   187   741  
Income Tax Expense (Benefit)   71   288  
Net income   $ 116   $ 453  
Diluted (in dollars per share) | $ / shares   $ 0.01   $ 0.02  
Restatement Adjustment [Member] | Expedited LTL [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   $ 8,202   $ 16,369  
Restatement Adjustment [Member] | Truckload Premium Services [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   5,265   10,567  
Restatement Adjustment [Member] | Pool Distribution [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   921   1,900  
Restatement Adjustment [Member] | Intermodal [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   1,970   2,586  
Restatement Adjustment [Member] | Elimination [Member] | Adjustments for New Accounting Pronouncement [Member]          
New Accounting Pronouncements or Change in Accounting Principle [Line Items]          
Operating revenue   $ 0   $ 0