Fair Value Measurement - Summary of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2023	Jun. 30, 2022
Assets
Cash equivalents:	$ 1,034,617	$ 1,446,541
Short-term investments:	1,073,013	1,108,493
Funds held for customers:	1,228,086	1,284,718
Beneficial interest derivative on card receivables sold		398
Total assets measured at fair value	3,668,577	4,008,410
Liabilities
Contingent consideration	11,066
Total liabilities measured at fair value	11,066
Money market funds
Assets
Cash equivalents:	1,034,617	1,435,111
Corporate bonds
Assets
Cash equivalents:		11,430
Short-term investments:	533,195	597,204
Funds held for customers:	632,183	807,685
U.S. treasury securities
Assets
Short-term investments:	411,635	421,728
Funds held for customers:	92,370	3,072
U.S. agency securities
Assets
Short-term investments:	38,508
Asset-backed securities
Assets
Short-term investments:	36,889	51,406
Funds held for customers:	90,217	69,912
Certificates of deposit
Assets
Short-term investments:	52,786	38,155
Funds held for customers:	386,090	397,533
Municipal bonds
Assets
Funds held for customers:		6,516
Restricted cash equivalents: \| Corporate bonds
Assets
Funds held for customers:	73,354	133,557
Restricted cash equivalents: \| Restricted cash equivalents:
Assets
Funds held for customers:	332,861	168,260
Restricted cash equivalents: \| Restricted cash equivalents: \| Money market funds
Assets
Funds held for customers:	256,287	34,703
Restricted cash equivalents: \| Certificates of deposit
Assets
Funds held for customers:	3,220
U.S. agency securities
Assets
Funds held for customers:	27,226
Level 1
Assets
Cash equivalents:	1,034,617	1,435,111
Short-term investments:	411,635	421,728
Funds held for customers:	92,370	3,072
Beneficial interest derivative on card receivables sold		0
Total assets measured at fair value	1,794,909	1,894,614
Liabilities
Contingent consideration	0
Total liabilities measured at fair value	0
Level 1 \| Money market funds
Assets
Cash equivalents:	1,034,617	1,435,111
Level 1 \| Corporate bonds
Assets
Cash equivalents:		0
Short-term investments:	0	0
Funds held for customers:	0	0
Level 1 \| U.S. treasury securities
Assets
Short-term investments:	411,635	421,728
Funds held for customers:	92,370	3,072
Level 1 \| U.S. agency securities
Assets
Short-term investments:	0
Level 1 \| Asset-backed securities
Assets
Short-term investments:	0	0
Funds held for customers:	0	0
Level 1 \| Certificates of deposit
Assets
Short-term investments:	0	0
Funds held for customers:	0	0
Level 1 \| Municipal bonds
Assets
Funds held for customers:		0
Level 1 \| Restricted cash equivalents: \| Corporate bonds
Assets
Funds held for customers:	0	0
Level 1 \| Restricted cash equivalents: \| Restricted cash equivalents:
Assets
Funds held for customers:	256,287	34,703
Level 1 \| Restricted cash equivalents: \| Restricted cash equivalents: \| Money market funds
Assets
Funds held for customers:	256,287	34,703
Level 1 \| Restricted cash equivalents: \| Certificates of deposit
Assets
Funds held for customers:	0
Level 1 \| U.S. agency securities
Assets
Funds held for customers:	0
Level 2
Assets
Cash equivalents:	0	11,430
Short-term investments:	661,378	686,765
Funds held for customers:	1,135,716	1,281,646
Beneficial interest derivative on card receivables sold		0
Total assets measured at fair value	1,873,668	2,113,398
Liabilities
Contingent consideration	0
Total liabilities measured at fair value	0
Level 2 \| Money market funds
Assets
Cash equivalents:	0	0
Level 2 \| Corporate bonds
Assets
Cash equivalents:		11,430
Short-term investments:	533,195	597,204
Funds held for customers:	632,183	807,685
Level 2 \| U.S. treasury securities
Assets
Short-term investments:	0	0
Funds held for customers:	0	0
Level 2 \| U.S. agency securities
Assets
Short-term investments:	38,508
Level 2 \| Asset-backed securities
Assets
Short-term investments:	36,889	51,406
Funds held for customers:	90,217	69,912
Level 2 \| Certificates of deposit
Assets
Short-term investments:	52,786	38,155
Funds held for customers:	386,090	397,533
Level 2 \| Municipal bonds
Assets
Funds held for customers:		6,516
Level 2 \| Restricted cash equivalents: \| Corporate bonds
Assets
Funds held for customers:	73,354	133,557
Level 2 \| Restricted cash equivalents: \| Restricted cash equivalents:
Assets
Funds held for customers:	76,574	133,557
Level 2 \| Restricted cash equivalents: \| Restricted cash equivalents: \| Money market funds
Assets
Funds held for customers:	0	0
Level 2 \| Restricted cash equivalents: \| Certificates of deposit
Assets
Funds held for customers:	3,220
Level 2 \| U.S. agency securities
Assets
Funds held for customers:	27,226
Level 3
Assets
Cash equivalents:	0	0
Short-term investments:	0	0
Funds held for customers:	0	0
Beneficial interest derivative on card receivables sold		398
Total assets measured at fair value	0	398
Liabilities
Contingent consideration	11,066
Total liabilities measured at fair value	11,066
Level 3 \| Money market funds
Assets
Cash equivalents:	0	0
Level 3 \| Corporate bonds
Assets
Cash equivalents:		0
Short-term investments:	0	0
Funds held for customers:	0	0
Level 3 \| U.S. treasury securities
Assets
Short-term investments:	0	0
Funds held for customers:	0	0
Level 3 \| U.S. agency securities
Assets
Short-term investments:	0
Level 3 \| Asset-backed securities
Assets
Short-term investments:	0	0
Funds held for customers:	0	0
Level 3 \| Certificates of deposit
Assets
Short-term investments:	0	0
Funds held for customers:	0	0
Level 3 \| Municipal bonds
Assets
Funds held for customers:		0
Level 3 \| Restricted cash equivalents: \| Corporate bonds
Assets
Funds held for customers:	0	0
Level 3 \| Restricted cash equivalents: \| Restricted cash equivalents:
Assets
Funds held for customers:	0	0
Level 3 \| Restricted cash equivalents: \| Restricted cash equivalents: \| Money market funds
Assets
Funds held for customers:	0	$ 0
Level 3 \| Restricted cash equivalents: \| Certificates of deposit
Assets
Funds held for customers:	0
Level 3 \| U.S. agency securities
Assets
Funds held for customers:	$ 0

Funds held for customers debt securities fair value disclosure.

No definition available.

Name:	bill_FundsHeldForCustomersDebtSecuritiesFairValueDisclosure
Namespace Prefix:	bill_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_AssetsFairValueDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI https://asc.fasb.org/extlink&oid=126975305&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126966325&loc=d3e6819-128478

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_FinancialLiabilitiesFairValueDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of financial and nonfinancial obligations.

+ References

+ Details

Name:	us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of interest continued to be held by a transferor after transferring financial assets to a third party.

+ References

No definition available.

+ Details

Name:	us-gaap_RetainedInterestFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=bill_RestrictedCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=bill_RestrictedCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: