Schedule III - Real Estate and Accumulated Depreciation - Changes in Accumulated Depreciation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance, beginning of period	$ 2,433,052,747	$ 2,278,291,645	$ 2,115,319,888
Depreciation for year	293,667,298	368,919,387	344,179,201
Sales	(239,277,690)	(86,798,173)	(97,063,934)
Transfers to unconsolidated joint ventures	(11,634,554)
Assets held for sale	(17,527,267)	(19,699,746)	(3,482,974)
Adjustment for fully depreciated assets	(72,992,791)	(107,660,366)	(80,660,536)
Balance, end of period	$ 2,385,287,743	$ 2,433,052,747	$ 2,278,291,645