Segment Reporting (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) segment	Sep. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Revenues	$ 132,583	$ 114,235	$ 392,977	$ 323,263
Trucking
Segment Reporting Information [Line Items]
Revenues	85,529	76,450	249,831	218,275
Operating Segments | Trucking
Segment Reporting Information [Line Items]
Revenues	86,801	76,811	251,332	219,013
Operating Segments | Foreign Countries | Trucking
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0