Schedule III - Real Estate and Accumulated Depreciation - Reconciliation of Gross Real Estate Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Balance, beginning of year	$ 13,592,440	$ 13,577,700	$ 13,539,921
Additions:
Acquisitions	351,135	437,227	634,080
Improvements	56,446	31,898	28,503
Deductions/Other:
Dispositions	(947,403)	(368,808)	(505,403)
Impairments	(81,078)	(84,278)	(82,292)
Reclassification to assets held for sale	(33,724)	(2,997)	(52,376)
Other	1,413	1,698	15,267
Balance, end of year	$ 12,939,229	$ 13,592,440	$ 13,577,700