Dispositions, Assets Held for Sale and Discontinued Operations (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Real property dispositions:
Total dispositions	$ 374,151	$ 418,759
Net loss (gain) on sales of properties	163,881	249,002
Proceeds from sales of real property	538,032	667,761
Escrow Deposits Related To Property Sales	27,803
Triple Net [Member]
Real property dispositions:
Total dispositions	295,365	246,116
Outpatient Medical [Member]
Real property dispositions:
Total dispositions	78,786	166,919	[1]
Land parcels [Member]
Real property dispositions:
Total dispositions	$ 0	$ 5,724

[1] (1) Primarily related to the disposition of an unconsolidated equity investment with Forest City Enterprises.