Debt and Preferred Equity Investments (Narrative)(Details)	12 Months Ended
	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($) segment
Preferred equity investment
Carrying Value	$ 1,640,412,000	$ 1,670,020,000
Number of portfolio segments of financial receivables (segment) | segment	1	1
Additional amount of financing receivables included in other assets	$ 99,500,000	$ 121,500,000
Junior Mortgage Participation Acquired in September 2014
Preferred equity investment
Carrying Value	$ 0