Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=br_LongTermDebtExcludingCurrentPortionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=br_Fiscal2019RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=br_Fiscal2019RevolvingCreditFacilityU.S.DollarTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=br_Fiscal2019RevolvingCreditFacilityMulticurrencyTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=br_Fiscal2014SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=br_Fiscal2016SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=br_Fiscal2020SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Borrowings - Schedule of Outstanding Borrowings (Details) - USD ($)	Sep. 30, 2020	Sep. 01, 2020	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2016	Aug. 31, 2013
Debt Instrument [Line Items]
Principal amount	$ 1,787,900,000
Current portion of long-term debt	0		$ 399,900,000
Long-term debt	1,776,100,000		1,387,600,000
Unused Available Capacity	962,100,000
Fair Value at September 30, 2020	1,912,200,000
Total debt	1,776,100,000		1,787,500,000
Long-term debt, excluding current portion
Debt Instrument [Line Items]
Principal amount	1,787,900,000
Long-term debt	1,776,100,000		1,387,600,000
Fair Value at September 30, 2020	1,912,200,000
Senior Notes
Debt Instrument [Line Items]
Principal amount	1,250,000,000.0
Long-term debt	1,238,200,000		1,237,800,000
Senior Notes \| Long-term debt, excluding current portion
Debt Instrument [Line Items]
Fair Value at September 30, 2020	1,374,200,000
Fiscal 2019 Revolving Credit Facility: \| Revolving Credit Facility
Debt Instrument [Line Items]
Principal amount	537,900,000
Long-term debt	537,900,000		149,800,000
Unused Available Capacity	962,100,000
Fair Value at September 30, 2020	537,900,000
Fiscal 2019 Revolving Credit Facility, U.S. Dollar Tranche \| Revolving Credit Facility
Debt Instrument [Line Items]
Principal amount	380,000,000.0
Long-term debt	380,000,000.0		0
Unused Available Capacity	720,000,000.0
Fair Value at September 30, 2020	380,000,000.0
Fiscal 2019 Revolving Credit Facility, Multicurrency Tranche \| Revolving Credit Facility
Debt Instrument [Line Items]
Principal amount	157,900,000
Long-term debt	157,900,000		149,800,000
Unused Available Capacity	242,100,000
Fair Value at September 30, 2020	157,900,000
Fiscal 2014 Senior Notes \| Senior Notes
Debt Instrument [Line Items]
Principal amount	0					$ 400,000,000.0
Current portion of long-term debt	0
Fair Value at September 30, 2020	0
Repayment of debt		$ 400,000,000.0
Fiscal 2014 Senior Notes \| Senior Notes \| Long-term debt, excluding current portion
Debt Instrument [Line Items]
Long-term debt			399,900,000
Fiscal 2016 Senior Notes \| Senior Notes
Debt Instrument [Line Items]
Principal amount	500,000,000.0				$ 500,000,000.0
Long-term debt	496,300,000
Fiscal 2016 Senior Notes \| Senior Notes \| Long-term debt, excluding current portion
Debt Instrument [Line Items]
Long-term debt			496,100,000
Fair Value at September 30, 2020	558,500,000
Fiscal 2020 Senior Notes \| Senior Notes
Debt Instrument [Line Items]
Principal amount	750,000,000.0			$ 750,000,000.0
Long-term debt	741,900,000
Fiscal 2020 Senior Notes \| Senior Notes \| Long-term debt, excluding current portion
Debt Instrument [Line Items]
Long-term debt			$ 741,700,000
Fair Value at September 30, 2020	$ 815,700,000