Summary of Significant Accounting Policies (Details) $ in Millions	Jun. 30, 2023 USD ($) Institution	Dec. 31, 2022 USD ($) Institution
Concentration of credit risk
Number of financial institutions holding cash and cash and cash equivalents \| Institution	3	3
Assignment and License Agreement \| Prepaid expenses and other current assets
Other Income
Receivables under agreements \| $	$ 0.0	$ 0.0

Represents the number of financial institutions that are holding the entity's cash and cash equivalents.

No definition available.

Name:	bcel_NumberOfFinancialInstitutionsHoldingCashAndCashEquivalents
Namespace Prefix:	bcel_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant