Earnings Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Income (loss) from continuing operations		$ 17,980	$ (28,248)
Income from sales of real estate	[1]	17,048	8,110
Net (income) loss attributable to noncontrolling interests		(95)	1,100
Preferred dividends		(8,124)	(12,830)
Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders for basic earnings per common share		26,809	(31,868)
Add: Effect of Series J convertible perpetual preferred stock		2,250	0
Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders for diluted earnings per common share		$ 29,059	$ (31,868)

[1] Income from sales of real estate represents gains from sales of real estate that do not qualify as discontinued operations