Reportable Segments - (Reconciliation of Net Income to Net Operating Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net Operating Income	$ 120,016	$ 120,642	$ 364,930	$ 305,790
Net operating income from unconsolidated joint ventures	(4,208)	(9,037)	(14,436)	(26,289)
Total Revenues	183,380	188,323	557,193	463,076
Reimbursed expenses	(373)	(1,290)	(1,216)	(3,269)
General and administrative expenses	(5,658)	(5,852)	(19,853)	(25,686)
Interest expense	(15,058)	(14,700)	(44,955)	(37,579)
Depreciation and amortization	(71,498)	(82,012)	(215,980)	(178,777)
Acquisition and transaction costs	0	(1,048)	(428)	(50,878)
Other expenses	(723)	(297)	(1,841)	(1,101)
Income from unconsolidated joint ventures	1,611	3,241	6,751	9,779
Gain (loss) on sales of investments in unconsolidated joint ventures	(59)	0	45,940	0
Gain (loss) on investment property transactions	(523)	(27)	90,192	14,388
Net income	28,255	20,692	226,800	34,115
Fee income
Segment Reporting Information [Line Items]
Total Revenues	4,350	7,494	13,772	23,298
Termination fee income
Segment Reporting Information [Line Items]
Total Revenues	372	3,575	3,755	4,285
Other
Segment Reporting Information [Line Items]
Total Revenues	$ 6	$ 3	$ 169	$ 154