Summary of Significant Accounting Policies and Basis of Presentation - Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation expense from continuing operations	$ 4,600,000	$ 5,000,000	$ 5,300,000
Impairment charges	$ 0	$ 0	$ 0
Computer laptops
Property, Plant and Equipment [Line Items]
Useful life	3 years
Desktops
Property, Plant and Equipment [Line Items]
Useful life	4 years
IT server, storage and network equipment
Property, Plant and Equipment [Line Items]
Useful life	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life	5 years
Purchased software
Property, Plant and Equipment [Line Items]
Useful life	3 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Useful life	10 years