The amount of gain on waiver of deferred underwriting fee recorded in accumulated deficit.

No definition available.

Name:	port_AccumulatedDeficitGainOnWaiverOfDeferredUnderwritingFees
Namespace Prefix:	port_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The additional non-redemption shares transferred.

+ References

No definition available.

+ Details

Name:	port_AdditionalNonRedemptionSharesTransferred
Namespace Prefix:	port_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate shares of not to redeem issued

+ References

No definition available.

+ Details

Name:	port_AggregateOfNonRedemptionSharesIssued
Namespace Prefix:	port_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate non-redemption shares transferred.

+ References

No definition available.

+ Details

Name:	port_AggregateOfNonRedemptionSharesTransferred
Namespace Prefix:	port_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the information pertaining to deferred underwriter fee per unit.

+ References

No definition available.

+ Details

Name:	port_DeferredUnderwriterFeePerUnit
Namespace Prefix:	port_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrecognized fee revenue received from underwriting that is deferred.

+ References

No definition available.

+ Details

Name:	port_DeferredUnderwritingCommissions
Namespace Prefix:	port_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of excess fair value of common stock transferred by Sponsor in non-cash investing and financing activities.

+ References

No definition available.

+ Details

Name:	port_ExcessFairValueOfCommonStockTransferred
Namespace Prefix:	port_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the maximum number of demands for registration of securities.

+ References

No definition available.

+ Details

Name:	port_MaximumNumberOfDemandsForRegistrationOfSecurities
Namespace Prefix:	port_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of units granted to the underwriters.

+ References

No definition available.

+ Details

Name:	port_NumberOfUnitsGrantedToUnderwriters
Namespace Prefix:	port_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares transferred to consummation of extension.

+ References

No definition available.

+ Details

Name:	port_SharesTransferredToConsummationOfExtension
Namespace Prefix:	port_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the amount of offering fees incurred and paid for underwriters.

+ References

No definition available.

+ Details

Name:	port_UnderwritingFees
Namespace Prefix:	port_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The underwriting option period.

+ References

No definition available.

+ Details

Name:	port_UnderwritingOptionPeriod
Namespace Prefix:	port_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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

- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=port_SponsorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Details)				3 Months Ended	12 Months Ended
Commitments and Contingencies (Details)	Aug. 22, 2022 USD ($)	Dec. 14, 2021 USD ($) $ / shares shares	Dec. 09, 2021 item	Mar. 31, 2025 USD ($) shares	Dec. 31, 2024 USD ($) shares	Feb. 29, 2024 shares	Feb. 14, 2024 shares	Jan. 31, 2024 shares	Jan. 12, 2024 shares	Dec. 13, 2023 shares	Nov. 14, 2023 shares	Oct. 11, 2023 shares	Sep. 30, 2023 shares	Jun. 09, 2023 shares	May 25, 2023 shares
Commitments and Contingencies
Maximum number of demands for registration of securities \| item			3
Underwriting option period		45 days
Underwriting fees \| $		$ 4,600,000
Deferred fee per Unit \| $ / shares		$ 0.35
Deferred underwriting commissions \| $		$ 8,050,000
Accumulated deficit on waiver of deferred underwriting fee \| $	$ 8,050,000
Class A common stock \| Sponsor
Commitments and Contingencies
Aggregate of non redemption shares issued															4,000,000
Class B common stock \| Sponsor
Commitments and Contingencies
Aggregate of non redemption shares transferred				1,499,996	1,499,996	1,499,996		1,499,996							1,499,996
Additional non redemption shares transferred				999,996	999,996		166,666		166,666	166,666	166,666	166,666	166,666		999,996
Shares transferred to consummation of extension														500,000	500,000
Excess fair value of shares transferred upon consummation of extension \| $				$ 1,209,879	$ 1,209,879
Over-allotment
Commitments and Contingencies
Number of units granted to underwriters		3,000,000
Shares issued underwriters		3,000,000