Acquired Card Receivables - Summary of Acquired Card Receivables Considered PCD Assets (Details) $ in Thousands	Jun. 01, 2021 USD ($)
Acquired Card Receivables [Abstract]
Purchase price	$ 3,855
Allowance for credit losses	2,082
Less: discount attributable to other factors	(79)
Par value	$ 5,858

Purchased credit deteriorated assets discounts attributable to other factors.

No definition available.

Name:	bill_PurchasedCreditDeterioratedAssetsDiscountsAttributableToOtherFactors
Namespace Prefix:	bill_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration