Schedule III: Real Estate and Accumulated Depreciation - Summary of Activity for Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real estate:
Balances at beginning of year	$ 13,473,573	$ 13,974,760	$ 14,330,257
Acquisition of real estate and development and improvements	1,093,903	995,443	987,135
Sales and/or transfers to assets held for sale and discontinued operations	(1,052,145)	(589,391)	(1,227,614)
Deconsolidation of real estate	(325,580)	(825,074)	(10,306)
Impairments	(49,729)	(37,274)	0
Other	(87,625)	(44,891)	(104,712)
Balances at end of year	13,052,397	13,473,573	13,974,760
Accumulated depreciation:
Balances at beginning of year	2,741,695	2,648,930	2,476,015
Depreciation expense	461,664	436,085	465,945
Sales and/or transfers to assets held for sale and discontinued operations	(239,231)	(115,195)	(239,112)
Deconsolidation of real estate	(43,525)	(152,572)	(5,868)
Other	(77,656)	(75,553)	(48,050)
Balances at end of year	$ 2,842,947	$ 2,741,695	$ 2,648,930