Schedule III - Real Estate and Accumulated Depreciation - Changes in Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Balance, beginning of year	$ 2,727,099	$ 2,622,879	$ 2,217,108
Additions:
Depreciation expense	318,535	352,531	497,511
Deductions/Other:
Dispositions	(65,930)	(201,319)	(57,346)
Impairments	(42,346)	(34,847)	(32,147)
Reclassified to assets held for sale	(15,652)	(7,602)	(400)
Other	(1,572)	(4,543)	(1,847)
Balance, end of year	$ 2,920,134	$ 2,727,099	$ 2,622,879