Summary of Significant Accounting Policies - PP&E and Impairment (Details)	12 Months Ended
Dec. 31, 2017
Computer hardware
Property and Equipment, Net
Estimated useful lives	3 years
Furniture and fixtures
Property and Equipment, Net
Estimated useful lives	7 years
Computer software
Property and Equipment, Net
Estimated useful lives	3 years
Office equipment
Property and Equipment, Net
Estimated useful lives	3 years

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration