Consolidated Statements of Operations (Unaudited) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Income Statement [Abstract]        
Revenue $ 470,085,693 $ 443,829,924 $ 885,837,967 $ 849,107,456
Costs and expenses:        
Transportation costs 388,472,528 358,652,347 729,726,541 683,103,064
Selling, general and administrative expenses 70,198,648 70,532,891 137,435,970 140,009,379
Depreciation and amortization 7,976,014 7,598,376 16,014,273 15,127,709
Income from operations 3,438,503 7,046,310 2,661,183 10,867,304
Interest expense (3,677,385) (3,524,166) (7,301,521) (7,027,561)
(Loss) Income before provision for income taxes (238,882) 3,522,144 (4,640,338) 3,839,743
Income tax (expense) benefit (6,484) (1,591,375) 1,522,929 (1,646,363)
Net (loss) income $ (245,366) $ 1,930,769 $ (3,117,409) $ 2,193,380
(Loss) Earnings per common share:        
Basic (in usd per share) $ (0.01) $ 0.07 $ (0.11) $ 0.08
Diluted (in usd per share) $ (0.01) $ 0.07 $ (0.11) $ 0.07