The Company and Its Significant Accounting Policies - Acquired Card Receivables (Details) - USD ($) $ in Millions	Jun. 30, 2022	Jun. 30, 2021
Accounting Policies [Abstract]
Allowance for potential credit losses for acquired card receivables	$ 5.4	$ 1.7

Allowance for potential credit losses for acquired card receivables.

No definition available.

Name:	bill_AllowanceForPotentialCreditLossesForAcquiredCardReceivables
Namespace Prefix:	bill_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant