Leases (Information Disclosed on Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Net book value	$ 469,068	$ 486,599
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	11,291	9,428
Accumulated depreciation	(4,805)	(3,992)
Net book value	6,486	5,436
Yard And Other [Member]
Property, Plant and Equipment [Line Items]
Cost	11,925
Accumulated depreciation	(3,055)
Net book value	8,870
Yard and Auto Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost		12,125
Accumulated depreciation		(2,585)
Net book value		9,540
Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Cost	23,216	21,553
Accumulated depreciation	(7,860)	(6,577)
Net book value	$ 15,356	$ 14,976	$ 14,976