Document and Entity Information - shares	9 Months Ended
	Mar. 31, 2021	Apr. 29, 2021
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Registrant Name	BILL.COM HOLDINGS, INC.
Entity Central Index Key	0001786352
Current Fiscal Year End Date	--06-30
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		83,201,830
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-39149
Entity Tax Identification Number	83-2661725
Entity Address, Address Line One	6220 America Center Drive, Suite 100
Entity Address, City or Town	San Jose
Entity Address, State or Province	CA
City Area Code	650
Local Phone Number	621-7700
Entity Address, Postal Zip Code	95002
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, $0.00001 par value
Security Exchange Name	NYSE
Trading Symbol	BILL