Schedule III - Real Estate And Accumulated Depreciation (Activity in Real Estate and Accumulated Depreciation)(Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in real estate
Balance at beginning of year	$ 16,681,602	$ 14,069,141
Property acquisitions	29,230	3,064,137	$ 2,428,259
Improvements	426,060	396,555	379,295
Retirements/disposals/deconsolidation	(4,393,560)	(848,231)	(1,072,193)
Balance at end of year	12,743,332	16,681,602	14,069,141
Aggregate cost of land, buildings and improvements before depreciation	9,200,000
Changes in accumulated depreciation
Balance at beginning of year	2,060,706	1,905,165
Depreciation for year	353,502	480,523	307,823
Retirements/disposals/deconsolidation	(149,514)	(324,982)	(48,898)
Balance at end of year	$ 2,264,694	$ 2,060,706	$ 1,905,165