Leases (Assets Recorded Under Capital Leases) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 13,717	$ 15,314
Accumulated depreciation	(6,748)	(7,832)
Net book value	6,969	7,482
Yard And Others [Member]
Property, Plant and Equipment [Line Items]
Cost	25,490	21,525
Accumulated depreciation	(7,998)	(5,749)
Net book value	17,492	15,776
Finance leases [Member]
Property, Plant and Equipment [Line Items]
Cost	39,207	36,839
Accumulated depreciation	(14,746)	(13,581)
Net book value	$ 24,461	$ 23,258