Other balance sheet items - Schedule of Goodwill (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2020
Goodwill [Roll Forward]
Gross carrying value as of beginning of period			$ 84,507,000	$ 84,507,000
Accumulated impairment losses as of beginning of period			(6,168,000)	(6,168,000)
Net carrying value as of beginning of period			78,339,000	78,339,000
Adjustments				1,756,000
Impairment losses		$ 0	(17,000,000.0)	(17,039,000)
Gross carrying value as of end of period	$ 86,263,000			86,263,000
Accumulated impairment losses as of end of period	(23,207,000)			(23,207,000)
Net carrying value as of end of period	63,056,000			63,056,000
Immaterial Error Correction
Goodwill [Roll Forward]
Impairment losses	(900,000)
Yucatán Peninsula
Goodwill [Roll Forward]
Gross carrying value as of beginning of period			51,731,000	51,731,000
Accumulated impairment losses as of beginning of period			(6,168,000)	(6,168,000)
Net carrying value as of beginning of period			45,563,000	45,563,000
Adjustments				0
Impairment losses				0
Gross carrying value as of end of period	51,731,000			51,731,000
Accumulated impairment losses as of end of period	(6,168,000)			(6,168,000)
Net carrying value as of end of period	45,563,000			45,563,000
Pacific Coast
Goodwill [Roll Forward]
Gross carrying value as of beginning of period			0	0
Accumulated impairment losses as of beginning of period			0	0
Net carrying value as of beginning of period			0	0
Adjustments				0
Impairment losses				0
Gross carrying value as of end of period	0			0
Accumulated impairment losses as of end of period	0			0
Net carrying value as of end of period	0			0
Dominican Republic
Goodwill [Roll Forward]
Gross carrying value as of beginning of period			0	0
Accumulated impairment losses as of beginning of period			0	0
Net carrying value as of beginning of period			0	0
Adjustments				0
Impairment losses				0
Gross carrying value as of end of period	0			0
Accumulated impairment losses as of end of period	0			0
Net carrying value as of end of period	0			0
Jamaica
Goodwill [Roll Forward]
Gross carrying value as of beginning of period			32,776,000	32,776,000
Accumulated impairment losses as of beginning of period			0	0
Net carrying value as of beginning of period			$ 32,776,000	32,776,000
Adjustments				1,756,000
Impairment losses				(17,039,000)
Gross carrying value as of end of period	34,532,000			34,532,000
Accumulated impairment losses as of end of period	(17,039,000)			(17,039,000)
Net carrying value as of end of period	$ 17,493,000			$ 17,493,000