Leases (Assets Recorded Under Capital Leases) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 13,047	$ 15,314
Accumulated depreciation	(6,096)	(7,832)
Net book value	6,951	7,482
Yard And Others [Member]
Property, Plant and Equipment [Line Items]
Cost	23,591	21,525
Accumulated depreciation	(6,725)	(5,749)
Net book value	16,866	15,776
Finance leases [Member]
Property, Plant and Equipment [Line Items]
Cost	36,638	36,839
Accumulated depreciation	(12,821)	(13,581)
Net book value	$ 23,817	$ 23,258