Reportable Segments (Reconciliation of Net Income to Net Operating Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting [Abstract]
Net Operating Income	$ 80,167	$ 59,513
Net operating income from unconsolidated joint ventures	(9,176)	(6,646)
Net operating income from discontinued operations	0	(25,318)
Fee income	1,936	2,199
Other income	5,426	390
Reimbursed expenses	(865)	(870)
General and administrative expenses	(6,182)	(8,243)
Interest expense	(9,741)	(5,439)
Depreciation and amortization	(54,884)	(16,541)
Acquisition and transaction costs	(1,930)	(19)
Other expenses	(404)	(355)
Income from unconsolidated joint ventures	581	1,834
Gain (loss) on sale of investment properties	(70)	14,190
Income from discontinued operations	0	8,101
Net income	$ 4,858	$ 22,796