Real Estate (Dispositions) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Land Sales	$ 15,191,000	$ 0	$ 0
Costs of Land Sales	12,840,000	0	0
Property sold, aggregate, carrying value	6,800,000
Income from sales of real estate	89,943,000	86,658,000	63,472,000
Impairment of long-lived assets to be disposed of or sold		1,800,000	22,600,000
Loss on transfer of interest to unconsolidated subsidiary	0	7,373,000	0
Net Lease Asset Two
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property sold, aggregate, carrying value	8,000,000
Income from sales of real estate	5,700,000
Net Lease
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties sold		5
Property sold, aggregate, carrying value		18,700,000
Income from sales of real estate		2,200,000
Impairment of long-lived assets to be disposed of or sold	3,600,000
Commercial Operating Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties sold		6
Property sold, aggregate, carrying value	29,400,000	72,600,000
Income from sales of real estate	4,600,000	18,600,000
Net Lease Asset One
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sales of real estate	7,800,000
Impairment of long-lived assets to be disposed of or sold	3,000,000
Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from sales of real estate		600,000
Number of real estate properties sold		3
Property sold, aggregate, carrying value		14,800,000
Income from sales of real estate		600,000
Condominium Units
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of other real estate	236,200,000	269,700,000	319,300,000
Income from sales of real estate	79,100,000	82,600,000	63,500,000
iStar Net Lease I LLC [Member] | Net Lease
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sales of real estate	10,100,000
Noncontrolling interest, ownership percentage by parent	72.00%
Transfer mortgage payable	26,000,000
iStar's ownership percentage	51.90%
iStar Net Lease I LLC [Member] | Net Lease Asset One
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sales of real estate	93,700,000
Real Estate Equity Investment Three | Net Lease
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
iStar's ownership percentage	50.00%
Real Estate Equity Investment Three | Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property Contributed, Aggregate, Carrying Value	9,500,000
Real Estate Equity Investment One | Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property Contributed, Aggregate, Carrying Value		24,100,000
Loss on transfer of interest to unconsolidated subsidiary		7,400,000
Real Estate Equity Investment Two | Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property Contributed, Aggregate, Carrying Value		2,800,000
iStar's ownership percentage	85.70%	50.00%
Marina Palms, LLC [Member] | Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from sales of real estate		3,400,000
Proceeds from partial sale of real estate		21,400,000
iStar's ownership percentage		47.50%
Land | Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property sold, aggregate, carrying value		18,900,000
Master Planned Community [Member] | Residential Real Estate
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties sold	3
Portfolio Lease Asset Sale [Member] | Net Lease
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property sold, aggregate, carrying value		$ 8,700,000