Reportable Segments (Reconciliation of Net Income to Net Operating Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Net income	$ 80,765	$ 219,959	$ 80,104
Net operating income from unconsolidated joint ventures	28,888	31,053	28,785
Net operating income from discontinued operations	0	0	78,591
Fee income	(10,089)	(8,632)	(8,347)
Other income	(3,270)	(11,518)	(1,050)
Reimbursed expenses	3,782	3,527	3,259
General and administrative expenses	22,040	27,523	25,592
Total interest expense	39,430	33,524	26,650
Depreciation and amortization	181,382	196,745	97,948
Acquisition and transaction costs	248	1,661	24,521
Other	556	1,796	5,888
(Gain) loss on extinguishment of debt	(8)	(2,258)	5,180
Income from unconsolidated joint ventures	(12,224)	(47,115)	(10,562)
Gain on sale of investment properties	(5,437)	(133,059)	(77,114)
Income from discontinued operations	0	0	(19,163)
Net Operating Income	$ 326,063	$ 313,206	$ 260,282