Related Party Arrangements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Arrangements
Management fees revenue	$ 5,599,000	$ 9,947,000	$ 11,050,000
Compensation expense	14,666,000	14,703,000	13,314,000
Unconsolidated real estate entities
Related Party Arrangements
Outstanding receivables	5,239,000	3,832,000
Non-employee directors
Related Party Arrangements
Payable to related parties	70,000
Payable to related parties in quarterly installments	17,500
Non-employee directors | Restricted stock and deferred stock awards
Related Party Arrangements
Payable to related parties	130,000
Compensation expense	1,216,000	1,135,000	1,049,000
Amount of deferred compensation	531,000	$ 488,000	$ 452,000
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
Non-employee directors | Restricted stock and deferred stock awards
Related Party Arrangements
Granted (in shares)	44,327	46,589