XML 116 R82.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Other Investments (Narrative) (Details) $ / shares in Units, $ in Thousands |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 02, 2019 USD ($) $ / shares shares | Dec. 31, 2019 USD ($) ft² building | Nov. 30, 2019 USD ($) shares | Aug. 31, 2019 USD ($) shares | May 31, 2019 USD ($) | Apr. 30, 2019 USD ($) | Feb. 28, 2019 | Dec. 31, 2018 USD ($) lease building | Jun. 30, 2018 USD ($) lease facility | May 31, 2018 USD ($) office_building | Apr. 30, 2017 USD ($) | Dec. 31, 2019 USD ($) ft² building | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2018 USD ($) | Jun. 30, 2018 USD ($) | Dec. 31, 2019 USD ($) ft² lease building | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Oct. 31, 2019 USD ($) | Jan. 31, 2019 USD ($) | Oct. 31, 2017 USD ($) | Aug. 31, 2017 USD ($) | Dec. 31, 2016 | Feb. 28, 2014
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of investor units purchased (in shares) | shares | 12,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investor units, purchase price per unit (in dollars per share) | $ / shares | $ 20.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to acquire equity method investments | $ 250,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 656,720 | $ 94,578 | $ 224,219 |  |  |  |  |  |
Restriction period on common stock received as payment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 years |  |  |  |  |  |  |  |
Commitment to extend credit |  | $ 150,000 |  |  |  |  |  |  |  |  |  | $ 150,000 |  |  |  |  |  |  |  |  |  | $ 150,000 |  |  |  |  |  |  |  |
Total gross carrying value of loans |  | $ 703,279 |  |  |  |  |  | $ 919,493 |  |  |  | 703,279 |  |  |  | $ 919,493 |  |  |  | $ 919,493 |  | 703,279 | 919,493 |  |  |  |  |  |  |
Number of industrial facilities sold | facility |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of ground leases structured and entered into | lease |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of ground leases sold | lease |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds from sales of real estate |  |  |  |  |  |  |  |  | $ 36,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income from sales of real estate |  |  |  |  |  |  |  |  | $ 24,500 |  |  |  |  |  |  |  |  |  |  |  |  | 236,623 | 126,004 | 92,049 |  |  |  |  |  |
Gain on consolidation of equity method investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 67,900 | 0 | 67,877 | 0 |  |  |  |  |  |
Increase in noncontrolling interest from consolidation of equity method investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 188,300 |  | 188,279 |  |  |  |  |  |  |
Increase in redeemable noncontrolling interest from consolidation of equity method investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,800 |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  |  |  |  | $ 128,888 | $ 145,338 | $ 98,468 | $ 106,802 | 140,165 | $ 122,141 | $ 171,571 | $ 364,245 |  |  | 479,496 | 798,122 | 679,202 |  |  |  |  |  |
Acquisitions of real estate assets |  |  |  |  | $ 56,700 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 240,487 | 19,454 | 6,600 |  |  |  |  |  |
Number of units in real estate property to be built | building |  | 3 |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  |  |
Term of contract remaining lease term |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6 years 2 months 12 days |  |  |  |  |  |  |  |
Net Lease |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income from sales of real estate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 224,700 | 45,000 | 87,500 |  |  |  |  |  |
Operating Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income from sales of real estate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 11,900 | 81,000 | 4,500 |  |  |  |  |  |
Great Oaks |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease term (in years) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 99 years |  |  |
Real estate leasehold improvement allowances |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,200 |  |  |
Net Lease Venture | Net Lease |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity interest (percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 51.90%
Equity method investment, related party ownership percentage |  | 0.60% |  |  |  |  |  |  |  |  |  | 0.60% |  |  |  |  |  |  |  |  |  | 0.60% |  |  |  |  |  |  |  |
Equity method investment, related party promote fee percentage |  | 50.00% |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |
Equity method investment, partner ownership percentage |  | 47.50% |  |  |  |  |  |  |  |  |  | 47.50% |  |  |  |  |  |  |  |  |  | 47.50% |  |  |  |  |  |  |  |
Net Lease Venture II |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity interest (percent) |  | 51.90% |  |  |  |  |  |  |  |  |  | 51.90% |  |  |  |  |  |  |  |  |  | 51.90% |  |  |  |  |  |  |  |
Net Lease Venture II | The Properties - Livermore CA |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties | building |  |  |  |  |  |  |  | 4 |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |
Acquisitions of real estate assets |  |  |  |  |  |  |  | $ 31,200 |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 81,800 |  |  |  |  |  |  |  |
Percentage of acquired properties leased (percent) |  |  |  |  |  |  |  | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  | 100.00% |  |  |  |  |  |  |  |
Number of leases | lease |  |  |  |  |  |  |  | 4 |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |
Area of properties (sq ft) | ft² |  | 168,636 |  |  |  |  |  |  |  |  |  | 168,636 |  |  |  |  |  |  |  |  |  | 168,636 |  |  |  |  |  |  |  |
Ground Lease, Atlanta medical office |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to extend credit, amount funded |  | $ 12,600 |  |  |  |  |  |  |  |  |  | $ 12,600 |  |  |  |  |  |  |  |  |  | $ 12,600 |  |  |  |  |  |  |  |
Interest income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,000 |  |  |  |  |  |  |  |
SAFE |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to acquire equity method investments |  |  |  |  |  |  |  |  |  |  | $ 55,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |
Expense reimbursements from related party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 700 |  | 2,100 |  |  |  |  |  |  |  |
Ground lease term (in years) |  |  |  | 99 years |  |  | 98 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ground Lease Tenant Acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to extend credit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 22,000 |  |  |  |  |
Ground Lease Multifamily Development SanJose CA |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,200 | 200 |  |  |  |  |  |  |
Ground Lease, 100 200 Glenridge Point |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,900 |  |  |  |  |  |  |  |
Ground Lease Conversion Washington DC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to extend credit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 13,300 |  |  |  |
Other real estate equity investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Related Party Transaction, Amounts of Transaction |  | $ 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investment realized gain (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 19,300 |  |  |  |  |  |  |  |
Other real estate equity investments | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity interest (percent) |  | 16.00% |  |  |  |  |  |  |  |  |  | 16.00% |  |  |  |  |  |  |  |  |  | 16.00% |  |  |  |  |  |  |  |
Other real estate equity investments | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity interest (percent) |  | 95.00% |  |  |  |  |  |  |  |  |  | 95.00% |  |  |  |  |  |  |  |  |  | 95.00% |  |  |  |  |  |  |  |
Other real estate equity investments | Land |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value |  | $ 42,900 |  |  |  |  |  | $ 65,300 |  |  |  | $ 42,900 |  |  |  | 65,300 |  |  |  | 65,300 |  | $ 42,900 | 65,300 |  |  |  |  |  |  |
Other real estate equity investments | Operating Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value |  | $ 61,700 |  |  |  |  |  | 65,600 |  |  |  | $ 61,700 |  |  |  | 65,600 |  |  |  | 65,600 |  | 61,700 | 65,600 |  |  |  |  |  |  |
Other Real Estate Equity Investment Aug 2018 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,800 | 1,100 |  |  |  |  |  |  |
Equity interest (percent) |  | 50.00% |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |
Payments for funding under loan commitments |  | $ 33,000 |  |  |  |  |  | 30,500 |  |  |  | $ 33,000 |  |  |  | 30,500 |  |  |  | 30,500 |  | $ 33,000 | 30,500 |  |  |  |  |  |  |
Other Real Estate Equity Investment Dec 2016 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity interest (percent) |  | 50.00% |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |
Other Real Estate Equity Investment Dec 2016 | Operating Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 600 | 2,100 | 1,900 |  |  |  |  |  |
Equity interest (percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |
Loans commitment |  |  |  |  |  |  |  | 27,000 |  |  |  |  |  |  |  | 27,000 |  |  |  | 27,000 |  |  | 27,000 |  |  |  |  |  |  |
Management Fees | Net Lease Venture | Other Income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,300 | 2,100 |  |  |  |  |  |
Management Fees | Net Lease Venture | Net Income Attributable To Noncontrolling Interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 700 |  | 1,500 |  |  |  |  |  |  |  |
Management Fees | Net Lease Venture II | Other Income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to extend credit, amount funded |  | $ 18,700 |  |  |  |  |  |  |  |  |  | $ 18,700 |  |  |  |  |  |  |  |  |  | 18,700 |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,500 | 400 |  |  |  |  |  |  |
Management Fees | SAFE |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenue from related party |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,800 |  | 7,500 |  |  |  |  |  |  |  |
Management fees waived |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,800 |  |  | 2,000 |  |  |  |  |  |
Safehold Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ground lease term (in years) |  |  |  | 99 years |  |  | 98 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Safehold Inc. | Great Oaks |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Forward purchase contract, purchase agreement, amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 34,000 |  |  |
Safehold Inc. | Ground Lease, Atlanta medical office |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,200 | 1,400 | $ 200 |  |  |  |  |  |
Safehold Inc. | Ground Lease, 100 200 Glenridge Point |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to extend credit |  |  |  |  |  |  |  |  |  | $ 19,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,400 |  |  |  |  |  |  |
Number of office buildings | office_building |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Leasehold First Mortgage | Great Oaks |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to extend credit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 80,500 |  |  |
Total gross carrying value of loans |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 80,500 |  |  |
Master Lease | Management Fees | Net Lease Venture II | Other Income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease term (in years) |  | 25 years |  |  |  |  |  |  |  |  |  | 25 years |  |  |  |  |  |  |  |  |  | 25 years |  |  |  |  |  |  |  |
Safehold Inc. | Ground Lease, Atlanta medical office |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commitment to extend credit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 24,000 |  |
Commitment to extend credit, amount funded |  | $ 38,900 |  |  |  |  |  |  |  |  |  | $ 38,900 |  |  |  |  |  |  |  |  |  | $ 38,900 |  |  |  |  |  | $ 18,400 |  |
Real Estate Investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value |  | 864,622 |  |  |  |  |  | 296,759 |  |  |  | 864,622 |  |  |  | 296,759 |  |  |  | 296,759 |  | 864,622 | 296,759 |  |  |  |  |  |  |
Real Estate Investment | Net Lease Venture |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value |  | 0 |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  | 0 | 0 |  |  |  |  |  |  |
Real Estate Investment | Net Lease Venture II |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value |  | $ 30,712 |  |  |  |  |  | 16,215 |  |  |  | $ 30,712 |  |  |  | 16,215 |  |  |  | 16,215 |  | $ 30,712 | 16,215 |  |  |  |  |  |  |
Real Estate Investment | SAFE |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to acquire equity method investments |  |  | $ 130,000 | $ 168,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Voting power cap threshold (percent) | 41.90% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Independent period | 3 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Standstill provisions (in years) | 2 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock transfer limitation maximum per agreement, other than widely distributed public offering (percent) | 20.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock company acquired (in shares) | shares |  |  | 3,800,000 | 6,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of ownership |  | 65.20% |  |  |  |  |  |  |  |  |  | 65.20% |  |  |  |  |  |  |  |  |  | 65.20% |  |  |  |  |  |  |  |
Real Estate Investment | Other real estate equity investments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value |  | $ 104,553 |  |  |  |  |  | $ 130,955 |  |  |  | $ 104,553 |  |  |  | $ 130,955 |  |  |  | $ 130,955 |  | $ 104,553 | $ 130,955 |  |  |  |  |  |  |
Fee percent of SAFE Equity up to $1.5 billion |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee as percent of equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.00% |  |  |  |  |  |  |  |
Fee percent of SAFE Equity up to $1.5 billion | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee equity threshold amount |  | 1,500,000 |  |  |  |  |  |  |  |  |  | 1,500,000 |  |  |  |  |  |  |  |  |  | $ 1,500,000 |  |  |  |  |  |  |  |
Fee percent of SAFE Equity between $1.5 billion and $3.0 billion |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee as percent of equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.25% |  |  |  |  |  |  |  |
Fee percent of SAFE Equity between $1.5 billion and $3.0 billion | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee equity threshold amount |  | 1,500,000 |  |  |  |  |  |  |  |  |  | 1,500,000 |  |  |  |  |  |  |  |  |  | $ 1,500,000 |  |  |  |  |  |  |  |
Fee percent of SAFE Equity between $1.5 billion and $3.0 billion | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee equity threshold amount |  | 3,000,000 |  |  |  |  |  |  |  |  |  | 3,000,000 |  |  |  |  |  |  |  |  |  | $ 3,000,000 |  |  |  |  |  |  |  |
Fee percent of SAFE Equity between $3.0 billion and $5.0 billion |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee as percent of equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.375% |  |  |  |  |  |  |  |
Fee percent of SAFE Equity between $3.0 billion and $5.0 billion | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee equity threshold amount |  | 3,000,000 |  |  |  |  |  |  |  |  |  | 3,000,000 |  |  |  |  |  |  |  |  |  | $ 3,000,000 |  |  |  |  |  |  |  |
Fee percent of SAFE Equity between $3.0 billion and $5.0 billion | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee equity threshold amount |  | 5,000,000 |  |  |  |  |  |  |  |  |  | 5,000,000 |  |  |  |  |  |  |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |
Fee percent of SAFE Equity over $5.0 billion |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee as percent of equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.50% |  |  |  |  |  |  |  |
Fee percent of SAFE Equity over $5.0 billion | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Management fee equity threshold amount |  | $ 5,000,000 |  |  |  |  |  |  |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |  |  | $ 5,000,000 |  |  |  |  |  |  |  |
Affiliated Entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate transaction price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 34,300 |  |  |  |  |  |  |  |
Payments to acquire land and develop asset |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,300 |  |  |  |  |  |  |  |
Assumption of loan in acquisition transaction |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 27,000 |  |  |  |  |  |  |  |
Affiliated Entity | Other Real Estate Equity Investment Dec 2016 | Operating Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate transaction price |  |  |  |  |  | $ 34,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to acquire land and develop asset |  |  |  |  |  | 7,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assumption of loan in acquisition transaction |  |  |  |  |  | $ 27,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition star_BusinessAcquisitionNumberOfSharesAcquired + References No definition available. + Details
Name: | star_BusinessAcquisitionNumberofSharesAcquired
Namespace Prefix: | star_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Stock Received as Payment Restriction Period + References No definition available. + Details
Name: | star_CommonStockReceivedasPaymentRestrictionPeriod
Namespace Prefix: | star_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Common Stock, Voting Rights, Investor Units Voting Power Threshold + References No definition available. + Details
Name: | star_CommonStockVotingRightsInvestorUnitsVotingPowerThreshold
Namespace Prefix: | star_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investment, Partner Ownership Percentage + References No definition available. + Details
Name: | star_EquityMethodInvestmentPartnerOwnershipPercentage
Namespace Prefix: | star_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investment, Related Party Ownership Percentage + References No definition available. + Details
Name: | star_EquityMethodInvestmentRelatedPartyOwnershipPercentage
Namespace Prefix: | star_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investment, Related Party Promote Fee Percentage + References No definition available. + Details
Name: | star_EquityMethodInvestmentRelatedPartyPromoteFeePercentage
Namespace Prefix: | star_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Forward Purchase Contract, Purchase Agreement, Amount + References No definition available. + Details
Name: | star_ForwardPurchaseContractPurchaseAgreementAmount
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Ground Lease, Structured And Entered Into, Number + References No definition available. + Details
Name: | star_GroundLeaseStructuredAndEnteredIntoNumber
Namespace Prefix: | star_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Ground Leases Sold Number + References No definition available. + Details
Name: | star_GroundLeasesSoldNumber
Namespace Prefix: | star_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Ground Leases, Term + References No definition available. + Details
Name: | star_GroundLeasesTerm
Namespace Prefix: | star_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Investor Units, Purchase Price Per Unit + References No definition available. + Details
Name: | star_InvestorUnitsPurchasePricePerUnit
Namespace Prefix: | star_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lessor, Operating Lease, Term of Contract, Remaining Lease Term + References No definition available. + Details
Name: | star_LessorOperatingLeaseTermofContractRemainingLeaseTerm
Namespace Prefix: | star_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Loans Commitments,Related Party + References No definition available. + Details
Name: | star_LoansCommitmentsRelatedParty
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Reflects the aggregate gross carrying amount of all categories of loans held in portfolio, after deducting deferred income, but before deducting the allowance for losses on loans. + References No definition available. + Details
Name: | star_LoansReceivableNetOfDeferredIncome
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Loans Receivable, Related Party + References No definition available. + Details
Name: | star_LoansReceivableRelatedParty
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Management Fees Waived + References No definition available. + Details
Name: | star_ManagementFeesWaived
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Noncontrolling Interest, Increase From Consolidation Of Equity Method Investment + References No definition available. + Details
Name: | star_NoncontrollingInterestIncreaseFromConsolidationOfEquityMethodInvestment
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number Of Investor Units Purchased + References No definition available. + Details
Name: | star_NumberOfInvestorUnitsPurchased
Namespace Prefix: | star_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Leases + References No definition available. + Details
Name: | star_NumberOfLeases
Namespace Prefix: | star_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Office Buildings + References No definition available. + Details
Name: | star_NumberOfOfficeBuildings
Namespace Prefix: | star_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Properties Acquired + References No definition available. + Details
Name: | star_NumberOfPropertiesAcquired
Namespace Prefix: | star_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Industrial Facilities Sold + References No definition available. + Details
Name: | star_NumberofIndustrialFacilitiesSold
Namespace Prefix: | star_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Units in Real Estate Property to be Built + References No definition available. + Details
Name: | star_NumberofUnitsinRealEstatePropertytobeBuilt
Namespace Prefix: | star_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage Of Acquired Properties Leased + References No definition available. + Details
Name: | star_PercentageOfAcquiredPropertiesLeased
Namespace Prefix: | star_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | star_RealEstateLeaseholdImprovementAllowances
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Redeemable Noncontrolling Interest, Increase From Consolidation Of Equity Method Investment + References No definition available. + Details
Name: | star_RedeemableNoncontrollingInterestIncreaseFromConsolidationOfEquityMethodInvestment
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Related Party Transaction, Commitment to Extend Credit, Amount Funded + References No definition available. + Details
Name: | star_RelatedPartyTransactionCommitmenttoExtendCreditAmountFunded
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Related Party Transaction, Commitment to Extend Credit to Customer + References No definition available. + Details
Name: | star_RelatedPartyTransactionCommitmenttoExtendCredittoCustomer
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Related Party Transaction, Management Fee, Percent of Equity + References No definition available. + Details
Name: | star_RelatedPartyTransactionManagementFeePercentofEquity
Namespace Prefix: | star_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Related Party Transaction, Management Fee, Shareholders' Equity Threshold Amount + References No definition available. + Details
Name: | star_RelatedPartyTransactionManagementFeeShareholdersEquityThresholdAmount
Namespace Prefix: | star_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Stock Transfer Limitation Per Agreement Other Than Widely Distributed Public Offering Maximum Percentage + References No definition available. + Details
Name: | star_StockTransferLimitationPerAgreementOtherThanWidelyDistributedPublicOfferingMaximumPercentage
Namespace Prefix: | star_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Stockholders Agreement Director Nominees Independent Period + References No definition available. + Details
Name: | star_StockholdersAgreementDirectorNomineesIndependentPeriod
Namespace Prefix: | star_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Stockholders Agreement Standstill Provision Term + References No definition available. + Details
Name: | star_StockholdersAgreementStandstillProvisionTerm
Namespace Prefix: | star_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Area of a real estate property. + References No definition available. + Details
Name: | us-gaap_AreaOfRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477 + Details
Name: | us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of liabilities incurred by the acquirer as part of consideration transferred in a business combination. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 25 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6405-128476 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477 + Details
Name: | us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of voting equity interests acquired in a business combination achieved in stages, including equity interests in the acquiree held by the acquirer immediately before the acquisition date and acquired at the acquisition date. + References No definition available. + Details
Name: | us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of gain (loss) on sale or disposal of an equity method investment. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(7)(c)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(9)(a)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 + Details
Name: | us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 25 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8813-108599 Reference 3: 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=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_EquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2443-110228 + Details
Name: | us-gaap_GainLossOnSaleOfProperties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of interest income earned from interest-bearing assets owed to the entity by related party. + References No definition available. + Details
Name: | us-gaap_InterestIncomeRelatedParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Term of lessor's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919359-209981 + Details
Name: | us-gaap_LessorOperatingLeaseTermOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow from the acquisition of a piece of land, anything permanently fixed to it, including buildings, structures on it and so forth; includes real estate intended to generate income for the owner; excludes real estate acquired for use by the owner. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireRealEstate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Cash received for the sale of real estate that is not part of an investing activity during the current period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfRealEstate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of transactions with related party during the financial reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864 + Details
Name: | us-gaap_RelatedPartyTransactionAmountsOfTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Reflects the sum of all other revenue and income realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period. + References No definition available. + Details
Name: | us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07.1(c)) -URI http://asc.fasb.org/extlink&oid=116637345&loc=SL114874292-224272 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1(e)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 + Details
Name: | us-gaap_RevenueFromRelatedParties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(1)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 + Details
Name: | us-gaap_Revenues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The gain (loss) recognized on initial consolidation of a variable interest entity (VIE) when the VIE is not a business (as defined). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5710-111685 + Details
Name: | us-gaap_VariableInterestEntityInitialConsolidationGainOrLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=star_NetLeaseAssetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=star_OperatingPropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_GreatOaksMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_IStarNetLeaseILLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_IStarNetLeaseIILLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=star_LivermoreCAPropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_GroundLeaseAtlantaMedicalCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_SAFEEquityMethodInvestmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_GroundLeaseTenantAcquisitionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_GroundLeaseMultifamilyDevelopmentSanJoseCAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_GroundLease100200GlenridgePointAtlantaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_GroundLeaseConversionWashingtonDCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_OtherRealEstateEquityInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=us-gaap_LandMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_OtherRealEstateEquityInvestmentAug2018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=star_OtherRealEstateEquityInvestmentDec2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=us-gaap_ManagementServiceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_OtherIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=star_NetIncomeAttributableToNoncontrollingInterestsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=star_SafeholdInc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=star_LeaseholdFirstMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=star_MasterLeaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=star_SafeholdInc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_RealEstateInvestmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | star_ManagementAgreementFeeStructureAxis=star_ManagementFeeTrancheOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | star_ManagementAgreementFeeStructureAxis=star_ManagementFeeTrancheTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | star_ManagementAgreementFeeStructureAxis=star_ManagementFeeTrancheThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | star_ManagementAgreementFeeStructureAxis=star_ManagementFeeTrancheFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |