Fair Value Measurements (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Impairment Charges From Continuing Operations
Impairment charges	$ 1,023	$ 570	$ 0
Nonrecurring | Level 3
Impairment Charges From Continuing Operations
Impairment charges	1,023	1,336	3,778
Nonrecurring | Level 3 | Equity investments in real estate
Impairment Charges From Continuing Operations
Fair Value Measurements	0	7,662	23,278
Impairment charges	0	766	3,778
Nonrecurring | Level 3 | Operating expenses
Impairment Charges From Continuing Operations
Impairment charges	1,023	570	0
Nonrecurring | Level 3 | Operating expenses | CMBS
Impairment Charges From Continuing Operations
Fair Value Measurements	1,478	1,808	0
Impairment charges	$ 1,023	$ 570	$ 0