The Company and Its Significant Accounting Policies - Additional Information (Details)				12 Months Ended
	Jun. 15, 2020 USD ($) $ / shares shares	Dec. 16, 2019 USD ($) $ / shares shares	Nov. 27, 2019	Jun. 30, 2020 USD ($) Segment Customer shares	Jun. 30, 2019 USD ($) Customer	Jun. 30, 2018 USD ($) Customer	Aug. 02, 2018
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Proceeds from issuance of common stock upon initial public offering, net of underwriting discounts and commissions and other offering costs		$ 225,500,000		$ 225,481,000
Reclassification of redeemable convertible preferred stock warrant liabilities to additional paid-in capital upon initial public offering		$ 1,400,000		$ 1,405,000
Net proceeds from follow-on public offering	$ 307,500,000
Reverse split of shares description				the Company filed an amendment to its amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s issued and outstanding redeemable convertible preferred stock, common stock and non-voting common stock on a 2-for-1 basis
Stock split, conversion ratio			2
Number of operating segments | Segment				1
Other-than-temporary impairment on short-term investments				$ 0	$ 0	$ 0
Impairment charges				$ 0	0	0
Offering period of purchase rights under ESPP				1 year
Advertising expenses				$ 5,800,000	3,700,000	800,000
ASU No. 2019-12
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]				true
Change in Accounting Principle, Accounting Standards Update, Adoption Date				Jun. 30, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]				true
ASU No. 2016-18
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]				true
Change in Accounting Principle, Accounting Standards Update, Adoption Date				Jun. 30, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]				true
ASU No. 2016-15
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]				true
Change in Accounting Principle, Accounting Standards Update, Adoption Date				Jun. 30, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]				true
Stock Options and RSUs
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Vesting term				4 years
Software Development
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Estimated useful lives				three years commencing on the first day of the month following when the software is ready for its intended use.
Software and Software Development Costs
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Software development costs capitalized				$ 600,000	1,600,000	$ 700,000
Unamortized internal-use software				$ 1,900,000	$ 2,300,000
Minimum
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Estimated useful lives				1 year
Deferred sales commissions are amortized				4 years
Maximum
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Estimated useful lives				5 years
Deferred sales commissions are amortized				6 years
Revenue Benchmark | Customer Concentration Risk
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Number of customers exceed 10% of revenue | Customer				0	0	0
Concentration percentage				10.00%	10.00%	10.00%
Common Stock
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Shares issued | shares				11,297,000
Redeemable convertible preferred stock converted | shares		52,434,505
IPO
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Shares issued | shares	4,330,000	11,297,058
Shares issued price to public per share | $ / shares	$ 74.25	$ 22.00
Underwriting discounts and commissions		$ 17,400,000
Other offering costs		$ 5,600,000
IPO | Other Assets
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Deferred offering costs					$ 400,000
Over-Allotment Option
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Shares issued | shares	1,080,000	1,473,529
Follow-On Public Offering
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Underwriting discounts and commissions	$ 12,900,000
Other offering costs	$ 1,100,000
Follow-On Public Offering | Common Stock
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Shares issued | shares				4,330,000
Bill Com Incorporation | BDC Payments Holdings, Inc
Organization Consolidation Basis Of Presentation Business Description And Accounting Policies [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent							100.00%