Dispositions, Assets Held for Sale and Discontinued Operations (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Real property dispositions:
Total dispositions	$ 128,768	$ 276,219
Net loss (gain) on sales of properties	1,530	246,956
Proceeds from sales of real property	130,298	523,175
Triple Net [Member]
Real property dispositions:
Total dispositions	128,768	105,274
Outpatient Medical [Member]
Real property dispositions:
Total dispositions	0	165,221	[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.