Fair Value Measurements - Reconciliation of unobservable inputs (Level 3) (Details) - Level 3 - Redeemable Series E Convertible Preferred Stock $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($)
Changes in Level 3 liabilities measured at fair value
Change in fair value	$ 21,688
Settlement of the Redeemable convertible Series E preferred stock forward contract liability	$ (21,688)

Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration