XML 54 R44.htm IDEA: XBRL DOCUMENT
v3.19.1

Business and Organization - Narrative (Details) $ in Billions | Mar. 31, 2019 USD ($)
--- | ---
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Investment across a range of real estate sectors over the past two decades (more than) | $ 40

X
- Definition Real Estate Investment + References No definition available. + Details
Name: | star_RealEstateInvestment
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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