Fair Value Disclosures (Estimated Fair Value of Notes Payable) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Real Estate Properties [Line Items]
Notes Payable, Net	$ 3,039,120	$ 2,627,088
Consolidated Properties [Member]
Real Estate Properties [Line Items]
Notes Payable, Net	3,039,120	2,627,088
Fair Value, Inputs, Level 2 [Member] | Consolidated Properties [Member]
Real Estate Properties [Line Items]
Notes Payable, Fair Value Disclosure	$ 3,125,709	$ 2,609,582
Notes Payable Fair Values Hypothetical Percent Increase In Interest Rates	1.00%
Impact Of Overall One Percent Increase In Interest Rates Decrease In Fair Values Of Notes Payable	$ 160,900
Impact Of Overall One Percent Increase In Interest Rates Decrease In Fair Values Of Notes Payable Percent	5.10%