Debt and Preferred Equity Investments (Preferred Equity Investments)(Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Preferred equity investment
Aggregate weighted average current yield (as a percent)	10.23%
Carrying Value, Net of Discounts and Deferred Origination Fees	$ 1,670,020	$ 1,408,804
Preferred equity investments
Preferred equity investment
Aggregate weighted average current yield (as a percent)	7.86%
Future Funding Obligations	$ 5,580
Senior Financing	131,669
Carrying Value, Net of Discounts and Deferred Origination Fees	42,176	132,995
Preferred Equity, March 2018
Preferred equity investment
Future Funding Obligations	0
Senior Financing	71,486
Carrying Value, Net of Discounts and Deferred Origination Fees	9,967	9,954
Preferred Equity, November 2018
Preferred equity investment
Future Funding Obligations	5,580
Senior Financing	60,183
Carrying Value, Net of Discounts and Deferred Origination Fees	32,209	0
Preferred Equity, Redeemed July 2015
Preferred equity investment
Future Funding Obligations	0
Senior Financing	0
Carrying Value, Net of Discounts and Deferred Origination Fees	$ 0	$ 123,041