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Business and Organization (Details) $ in Billions | 9 Months Ended
--- | ---
Sep. 30, 2016 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Investment across a range of real estate sectors over the past two decades (more than) | $ 35

X
- Definition Represents the amount invested across a range of real estate sectors by the entity over a period of time. + References No definition available. + Details
Name: | star_RealEstateInvestment
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration