Debt Instrument, Interest Coverage Ratio

No definition available.

Name:	bsig_DebtInstrumentInterestCoverageRatio
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Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

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+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
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
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Balance Type:	na
Period Type:	duration

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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.

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+ Details

Name:	us-gaap_LongTermDebt
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

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Balance Type:	credit
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Borrowings and Debt (Details)			3 Months Ended
Borrowings and Debt (Details)	Mar. 07, 2022	Jan. 18, 2022 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Loss on extinguishment of debt			$ 3,200,000	$ 0
Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Carrying value			273,200,000		$ 394,900,000
Fair value			265,300,000		412,900,000
Line of Credit \| Revolving credit facility
Debt Instrument [Line Items]
Face amount			125,000,000
Interest coverage ratio	4.0
Line of Credit \| Revolving credit facility \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.25%
Line of Credit \| Revolving credit facility \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	0.375%
Line of Credit \| Revolving credit facility \| Fed Funds Effective Rate Overnight Index Swap Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Line of Credit \| Revolving credit facility \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Line of Credit \| Revolving credit facility \| London Interbank Offered Rate (LIBOR) \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
Line of Credit \| Revolving credit facility \| London Interbank Offered Rate (LIBOR) \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Line of Credit \| Revolving credit facility \| Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Carrying value			88,000,000.0		0
Fair value			88,000,000.0		0
Line of Credit \| Revolving credit facility \| Revolving Credit Facility Expiring August 22, 2022 \| Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Carrying value			88,000,000.0		0
Fair value			88,000,000.0		0
Senior notes \| Senior Notes, 4.80%, due 2026
Debt Instrument [Line Items]
Face amount			$ 275,000,000
Stated interest rate			4.80%
Senior notes \| Senior Notes, 4.80%, due 2026 \| Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Carrying value			$ 273,200,000		273,100,000
Fair value			265,300,000		286,500,000
Senior notes \| Senior Notes, 5.125%, due 2031
Debt Instrument [Line Items]
Face amount			$ 125,000,000
Stated interest rate		5.125%	5.125%
Debt repayments		$ 125,000,000
Loss on extinguishment of debt		$ 3,200,000
Senior notes \| Senior Notes, 5.125%, due 2031 \| Fair Value, Inputs, Level 2
Debt Instrument [Line Items]
Carrying value			$ 0		121,800,000
Fair value			$ 0		$ 126,400,000