Summary of Significant Accounting Policies - Fixed assets, Net (Details)	12 Months Ended
Dec. 31, 2020
Software, including software development costs \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	3
Software, including software development costs \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	5 years
Computer and communications equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	3
Computer and communications equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	5 years

Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 35
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68071081&loc=d3e1205-110223

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790

Name:	us-gaap_PropertyPlantAndEquipmentEstimatedUsefulLives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration