Operating Expenses (Schedule of Direct Operating Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Expenses [Abstract]
Ancillary and logistical service expenses	$ 14,580	$ 11,527
Employee compensation expenses	9,019	5,476
Buildings, facilities and technology expenses	2,627	1,546
Travel, advertising and promotion expenses	6,808	4,656
Other costs of services	3,623	1,135
Cost of Services, Total	$ 36,657	$ 24,340