Income Taxes - Changes in Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets, Valuation Allowance [Roll Forward]
Valuation allowance beginning balance	$ 46,732	$ 30,275	$ 15,468
Increase of valuation allowance	28,240	16,457	14,807
Valuation allowance ending balance	$ 74,972	$ 46,732	$ 30,275

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319

Name:	us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant