Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 23,273	$ 41,411
Accumulated depreciation	(19,698)	(37,045)
Property and equipment—net	3,575	4,366
Information technology
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 21,423	34,611
Information technology | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	2 years
Information technology | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 0	4,568
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	2 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,850	1,964
Furniture and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	2 years
Furniture and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
Building improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 0	$ 268
Building improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	2 years
Building improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years