Note 15 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tour revenues		$ 70,609	$ 87,242	$ 69,473	$ 82,410	$ 63,221	$ 84,584	$ 55,571	$ 63,128		$ 309,734	$ 266,504	$ 242,346
Tour revenues, change											43,230	$ 24,158
Tour revenues, percentage change										16.00%		10.00%
Operating income											25,338	$ 10,744	13,981
Operating income, change											14,594	$ (3,237)
Operating income, percentage change										136.00%		(23.00%)
Depreciation and amortization											20,768	$ 17,351	18,420
Total depreciation and amortization, change											$ 3,417	$ (1,069)
Total depreciation and amortization, percentage change											20.00%	(6.00%)
Lindblad		473,409				424,348				$ 473,409	$ 473,409	$ 424,348
Intangibles, net		7,975				9,554				7,975	7,975	9,554
Goodwill		22,105				22,105				$ 22,105	22,105	22,105
Lindblad Segment [Member]
Tour revenues											246,334	216,815	207,836
Tour revenues, change											29,519	$ 8,979
Tour revenues, percentage change										14.00%		4.00%
Operating income											19,798	$ 7,292	11,794
Operating income, change											12,506	$ (4,502)
Operating income, percentage change										172.00%		(38.00%)
Depreciation and amortization											19,277	$ 15,969	17,569
Total depreciation and amortization, change											$ 3,308	$ (1,600)
Total depreciation and amortization, percentage change											21.00%	(9.00%)
Lindblad		409,622				371,080				$ 409,622	$ 409,622	$ 371,080
Intangibles, net		4,050				4,776				4,050	4,050	4,776
Goodwill
Natural Habitat Segment [Member]
Tour revenues	[1]										63,400	49,689	34,510
Tour revenues, change	[1]										13,711	$ 15,179
Tour revenues, percentage change	[1]									28.00%		44.00%
Operating income	[1]										5,540	$ 3,452	2,187
Operating income, change	[1]										2,088	$ 1,265
Operating income, percentage change	[1]									60.00%		58.00%
Depreciation and amortization	[1]										1,491	$ 1,382	$ 851
Total depreciation and amortization, change	[1]										$ 109	$ 531
Total depreciation and amortization, percentage change	[1]										8.00%	62.00%
Lindblad		63,787				53,268				$ 63,787	$ 63,787	$ 53,268
Intangibles, net		3,925				4,778				3,925	3,925	4,778
Goodwill		$ 22,105				$ 22,105				$ 22,105	$ 22,105	$ 22,105

[1] The 2016 Natural Habitat segment results represent activity from acquisition date of May 2016 through December 31, 2016.