Property and Equipment Table (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Leasehold improvements	$ 21,975	$ 22,199
Office furniture and equipment	6,102	6,117
Total cost	108,231	103,490
Accumulated depreciation	(70,561)	(64,210)
Property and equipment, net	37,670	39,280
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Other, Gross	62,303	57,277
Transportation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Other, Gross	$ 17,851	$ 17,897
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	1 year
Minimum [Member] | Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	1 year
Minimum [Member] | Transportation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	3 years
Minimum [Member] | Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	4 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	15 years
Maximum [Member] | Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	10 years
Maximum [Member] | Transportation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	12 years
Maximum [Member] | Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful Life	15 years