Leases (Assets Recorded Under Capital Leases) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 15,820	$ 16,597
Accumulated depreciation	(8,660)	(8,317)
Net book value	7,160	8,280
Yard And Others [Member]
Property, Plant and Equipment [Line Items]
Cost	31,670	28,234
Accumulated depreciation	(13,903)	(10,865)
Net book value	17,767	17,369
Finance leases [Member]
Property, Plant and Equipment [Line Items]
Cost	47,490	44,831
Accumulated depreciation	(22,563)	(19,182)
Net book value	$ 24,927	$ 25,649