Goodwill - Changes in carrying amount of goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill
Gross goodwill amount	$ 169,843,000	$ 157,466,000	$ 158,119,000
Accumulated impairment	(49,623,000)	(44,123,000)	(44,123,000)
Changes in the carrying amount of goodwill
Balance at the beginning of the period	113,343,000	113,996,000
Impairment	(5,500,000)	0	(9,796,000)
Foreign currency translation adjustment	6,877,000	(653,000)
Balance at the end of the period	120,220,000	113,343,000	113,996,000
Europe
Goodwill
Gross goodwill amount	70,660,000	64,459,000	64,263,000
Accumulated impairment	(14,202,000)	(14,202,000)	(14,202,000)
Changes in the carrying amount of goodwill
Balance at the beginning of the period	50,257,000	50,061,000
Impairment	0	0
Foreign currency translation adjustment	6,201,000	196,000
Balance at the end of the period	56,458,000	50,257,000	50,061,000
North America
Goodwill
Gross goodwill amount	71,601,000	66,101,000	66,101,000
Accumulated impairment	(21,610,000)	(16,110,000)	(16,110,000)
Changes in the carrying amount of goodwill
Balance at the beginning of the period	49,991,000	49,991,000
Impairment	(5,500,000)	0
Foreign currency translation adjustment	0	0
Balance at the end of the period	49,991,000	49,991,000	49,991,000
Rest of world
Goodwill
Gross goodwill amount	20,530,000	20,581,000	19,975,000
Accumulated impairment	(13,149,000)	(13,149,000)	(13,149,000)
Changes in the carrying amount of goodwill
Balance at the beginning of the period	7,432,000	6,826,000
Impairment	0	0
Foreign currency translation adjustment	(51,000)	606,000
Balance at the end of the period	7,381,000	7,432,000	6,826,000
Owned trains and cruises
Goodwill
Gross goodwill amount	7,052,000	6,325,000	7,780,000
Accumulated impairment	(662,000)	(662,000)	(662,000)
Changes in the carrying amount of goodwill
Balance at the beginning of the period	5,663,000	7,118,000
Impairment	0	0
Foreign currency translation adjustment	727,000	(1,455,000)
Balance at the end of the period	6,390,000	$ 5,663,000	$ 7,118,000
Cap Juluca
Changes in the carrying amount of goodwill
Impairment	(5,500,000)
Balance at the end of the period	5,500,000
Cap Juluca | North America
Changes in the carrying amount of goodwill
Balance at the end of the period	$ 5,500,000