Acquired Card Receivables - Schedule of Acquired Card Receivables (Details) $ in Thousands	Jun. 30, 2021 USD ($)
Acquired Card Receivables [Abstract]
Gross amount of acquired card receivables	$ 148,833
Less: allowance for credit losses	(1,740)
Total	$ 147,093

Acquired card receivables allowance for credit losses.

No definition available.

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