Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment	$ 44,764	$ 55,959
Less accumulated depreciation and amortization	(30,678)	(43,141)
Property and equipment, net of accumulated depreciation and amortization	14,086	12,818
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	6,432	13,584
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment	24,933	28,752
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment	1,379	2,397
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	4,680	3,969
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	$ 7,340	$ 7,257
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Minimum | Computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Minimum | Computer software
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Minimum | Office equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Minimum | Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Maximum | Computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Maximum | Computer software
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Maximum | Office equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Maximum | Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years