The Company and Its Significant Accounting Policies - Acquired Card Receivables (Details)	Jun. 30, 2026
Accounting Policies [Abstract]
Participation interest required to be purchased	1
Number of days delinquent to become charged-off	120 days

Acquired Card Receivables, Participation Interest Required To Be Purchased

No definition available.

Name:	bill_AcquiredCardReceivablesParticipationInterestRequiredToBePurchased
Namespace Prefix:	bill_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant