Operating expenses (Schedule of Direct Operating Expenses) (Details) - Service Revenues [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Ancillary and logistical service expenses	$ 14,418	$ 11,433	$ 38,619	$ 38,521
Employee compensation expenses	16,912	14,253	49,878	43,736
Buildings, facilities and technology expenses	2,560	2,496	9,439	7,501
Travel, advertising and promotion expenses	4,351	3,205	16,722	13,022
Other costs of services	3,280	3,721	10,917	11,495
Total direct expenses	$ 41,521	$ 35,108	$ 125,575	$ 114,275