Leases (Assets Recorded Under Capital Leases) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 16,161	$ 16,597
Accumulated depreciation	(7,936)	(8,317)
Net book value	8,225	8,280
Yard And Others [Member]
Property, Plant and Equipment [Line Items]
Cost	29,275	28,234
Accumulated depreciation	(12,278)	(10,865)
Net book value	16,997	17,369
Finance leases [Member]
Property, Plant and Equipment [Line Items]
Cost	45,436	44,831
Accumulated depreciation	(20,214)	(19,182)
Net book value	$ 25,222	$ 25,649