XML 18 R6.htm IDEA: XBRL DOCUMENT
v3.21.2

Condensed Consolidated Statement of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (Unaudited) $ in Thousands | 9 Months Ended
--- | ---
Sep. 30, 2020 USD ($)
Convertible Preferred Stock |
Net issuance cost | $ 533

X
- Definition Temporary equity issuance costs. + References No definition available. + Details
Name: | lyel_TemporaryEquityIssuanceCosts
Namespace Prefix: | lyel_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_ConvertiblePreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |