Debt Securities, Trading, Excluding Short-Term Investments, Weighted-Average Duration

No definition available.

Name:	spnt_DebtSecuritiesTradingExcludingShortTermInvestmentsWeightedAverageDuration
Namespace Prefix:	spnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Securities, Trading, Weighted-Average Duration

+ References

No definition available.

+ Details

Name:	spnt_DebtSecuritiesTradingWeightedAverageDuration
Namespace Prefix:	spnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Investments In Related Party Investment Funds, Eligible Withdrawal Period One

+ References

No definition available.

+ Details

Name:	spnt_InvestmentsInRelatedPartyInvestmentFundsEligibleWithdrawalPeriodOne
Namespace Prefix:	spnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Investments In Related Party Investment Funds, Eligible Withdrawal Period Two

+ References

No definition available.

+ Details

Name:	spnt_InvestmentsInRelatedPartyInvestmentFundsEligibleWithdrawalPeriodTwo
Namespace Prefix:	spnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Investments In Related Party Investment Funds, Eligible Withdrawal Threshold , Percentage Of Aggregate Opening Balance And Aggregate Capital Contributions

+ References

No definition available.

+ Details

Name:	spnt_InvestmentsInRelatedPartyInvestmentFundsEligibleWithdrawalThresholdPercentageOfAggregateOpeningBalanceAndAggregateCapitalContributions
Namespace Prefix:	spnt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Other Long-term Investments, Distribution Receivable

+ References

No definition available.

+ Details

Name:	spnt_OtherLongTermInvestmentsDistributionReceivable
Namespace Prefix:	spnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Other Long-Term Investments, Number Of Funds Held

+ References

No definition available.

+ Details

Name:	spnt_OtherLongTermInvestmentsNumberOfFundsHeld
Namespace Prefix:	spnt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=SL6742756-110258

+ Details

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

- Definition

Amount of long-term investments classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_OtherLongTermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	spnt_CreditRatingAxis=spnt_AAARatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	spnt_CreditRatingAxis=spnt_AARatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	spnt_CreditRatingAxis=spnt_ARatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubprimeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Investments - Narrative (Details)		9 Months Ended	12 Months Ended
Investments - Narrative (Details)	Aug. 06, 2020	Sep. 30, 2021 USD ($) fund	Dec. 31, 2020 USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Weighted average duration of debt securities		1 year 7 months 6 days	10 years 6 months
Weighted average duration of debt securities, excluding short-term investments		2 years 2 months 12 days	10 years 6 months
Debt securities		$ 2,100,900,000	$ 101,300,000
Other long-term investments		454,500,000	4,000,000.0
Third Point Enhanced LP
Debt and Equity Securities, FV-NI [Line Items]
Eligible withdrawal period after the closing date	5 years
Eligible withdrawal period at each successive anniversary of the closing date	2 years
Eligible withdrawal threshold, percentage of aggregate opening balance and aggregate capital contributions	20.00%
Investments in related investment party funds, unfunded commitments		0
Third Point Venture Offshore Fund I LP
Debt and Equity Securities, FV-NI [Line Items]
Investments in related investment party funds, unfunded commitments		$ 16,000,000
Hedge funds
Debt and Equity Securities, FV-NI [Line Items]
Number of funds held as investments \| fund		8
Other long-term investments		$ 84,300,000
Investments in related investment party funds, unfunded commitments		$ 0
Private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Number of funds held as investments \| fund		20
Other long-term investments		$ 128,000,000.0
Investments in related investment party funds, unfunded commitments		32,100,000
Largest investment in a single fund
Debt and Equity Securities, FV-NI [Line Items]
Other long-term investments		35,600,000
Hedge funds and private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Other long-term investments		212,300,000	0
Distribution receivable		11,900,000
Investments in related investment party funds, unfunded commitments		32,100,000
AAA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities		661,800,000	53,200,000
AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities		901,500,000	0
A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities		281,000,000.0	9,100,000
Sub-prime
Debt and Equity Securities, FV-NI [Line Items]
Debt securities		35,000,000
Sub-prime \| AAA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities		15,100,000
Sub-prime \| AA
Debt and Equity Securities, FV-NI [Line Items]
Debt securities		10,400,000
Sub-prime \| A
Debt and Equity Securities, FV-NI [Line Items]
Debt securities		$ 9,500,000	$ 8,700,000