Related Party Arrangements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Arrangements
Management fees revenue	$ 9,947,000	$ 11,050,000	$ 11,502,000
Compensation expense	14,703,000	13,314,000	17,775,000
Unconsolidated real estate entities
Related Party Arrangements
Outstanding receivables	3,832,000	6,868,000
Non-employee directors
Related Party Arrangements
Payable to related parties	60,000
Payable to related parties in quarterly installments	15,000
Non-employee directors | Restricted stock and deferred stock awards
Related Party Arrangements
Payable to related parties	130,000
Compensation expense	1,135,000	1,049,000	992,000
Amount of deferred compensation	$ 488,000	$ 452,000	$ 417,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Conversion of Shares	46,589
Lead Independent Director
Related Party Arrangements
Payable to related parties	$ 25,000
Payable to related parties in quarterly installments	6,250
Non-employees directors serving as a chairperson
Related Party Arrangements
Payable to related parties	10,000
Payable to related parties in quarterly installments	$ 2,500