Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Loss Contingency Accrual, Period Increase (Decrease)	$ 3,000
Loss Contingency Accrual	$ 3,000
Projects in various stages of development	10
Units in various stages of development	3,989
Consolidated Project Under Development Commitment Fund	$ 762,300
Various stages of development with estimated completion dates ranging through September 30, 2017	Sep. 30, 2017
Number Of Operating Properties and Land Parcels Under Long Term Ground Leases	12
Total operating lease payments	$ 17,800	$ 14,700	$ 13,200
Compensation expense, Recognized	400	$ 500	$ 500
Operating Leases:
Minimum Rent Payments Due, Year 1	(15,723)
Minimum Rent Payments Due, Year 2	(15,721)
Minimum Rent Payments Due, Year 3	(15,712)
Minimum Rent Payments Due, Year 4	(15,567)
Minimum Rent Payments Due, Year 5	(15,158)
Minimum Rent Payments Due, Thereafter	(839,521)
Minimum Rent Payments Due, Total	(917,402)
Operating Leases, Future Minimum Payments Receivable, Current	70,360
Operating Leases, Future Minimum Payments Receivable, in Two Years	56,759
Operating Leases, Future Minimum Payments Receivable, in Three Years	50,134
Operating Leases, Future Minimum Payments Receivable, in Four Years	45,956
Operating Leases, Future Minimum Payments Receivable, in Five Years	42,050
Operating Leases, Future Minimum Payments Receivable, Thereafter	210,149
Operating Leases, Future Minimum Payments Receivable	475,408
Other Long-Term Liabilities:
Deferred Compensation Due, Year 1	(1,387)
Deferred Compensation Due, Year 2	(1,724)
Deferred Compensation Due, Year 3	(1,724)
Deferred Compensation Due, Year 4	(1,130)
Deferred Compensation Due, Year 5	(1,080)
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter	(4,797)
Deferred Compensation Due, Total	$ (11,842)
Unconsolidated Properties [Member]
Number Of Unconsolidated Projects	2