Name:	star_DebtInstrumentTermOfVariableRate
Namespace Prefix:	star_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The percentage of estimated total annualized cost of capital.

No definition available.

Name:	star_LineOfCreditFacilityAnnualizedCostOfCapitalEstimatedPercentage
Namespace Prefix:	star_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts can be increased currently outstanding under the facility.

No definition available.

Name:	star_LineOfCreditFacilityMaximumBorrowingCapacityCanBeIncreased
Namespace Prefix:	star_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

No definition available.

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

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/exampleRef
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Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Indicates type of variable interest rate on debt instrument.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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Name:	us-gaap_DebtInstrumentVariableInterestRateTypeExtensibleEnumeration
Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

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

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

Name:	us-gaap_LineOfCreditFacilityAxis=star_SterlingNationalBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_WebsterBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_BlueRidgeBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_DimeCommunityBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_FirstFoundationBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_MitsubishiHCCapitalAmericaIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_WoodforestNationalBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_ForbrightBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_PeapackGladstoneBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_HanmaiBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_AppleBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=star_EastWestBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: