Note 3 - Revenues - Disaggregation of Revenues by Type (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Tour revenues	100.00%	0.00%	100.00%	100.00%
Guest Ticket [Member]
Tour revenues	91.00%	0.00%	89.00%	89.00%
Guest Ticket [Member] | Sales Channel, Directly to Consumer [Member]
Tour revenues	59.00%	0.00%	58.00%	42.00%
Guest Ticket [Member] | Sales Channel, National Geographic [Member]
Tour revenues	11.00%	0.00%	10.00%	18.00%
Guest Ticket [Member] | Sales Channel, Agencies [Member]
Tour revenues	19.00%	0.00%	19.00%	24.00%
Guest Ticket [Member] | Sales Channel, Affinity [Member]
Tour revenues	2.00%	0.00%	2.00%	5.00%
Other Tour [Member]
Tour revenues	9.00%	0.00%	11.00%	11.00%