Schedule III - Real Estate and Accumulated Depreciation - Summary of Changes in Real Estate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in total real estate
Balance, beginning of year	$ 25,386,425	$ 28,542,697	$ 27,675,383
Acquisitions and development	710,960	832,803	964,645
Improvements	204,113	174,981	186,104
Dispositions and other	(274,602)	(4,164,056)	(283,435)
Balance, end of year	$ 26,026,896	$ 25,386,425	$ 28,542,697