Discontinued Operations (Summary Of Income From Discontinued Operations And Related Realized And Unrealized Gains (Losses)) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Discontinued Operations [Abstract]
Total revenues	$ 175,938,000	$ 164,891,000	$ 157,171,000
Operating and other expenses	(70,640,000)	(68,093,000)	(62,654,000)
Depreciation and amortization	(72,602,000)	(62,605,000)	(62,849,000)
Interest expense	(5,240,000)	(6,238,000)	(8,790,000)
Loss from early extinguishment of debt		(1,821,000)
Income from discontinued operations	27,456,000	26,134,000	22,878,000
Unrealized losses on disposition of rental property	(144,090,000)
Realized gains on disposition of rental property	7,916,000
Realized gains (losses) and unrealized losses on disposition of rental property and impairments, net	(136,174,000)
Total discontinued operations, net	(108,718,000)	26,134,000	22,878,000
Valuation allowance	9,800,000		$ (5,300,000)
Accumulated depreciation	$ 558,617,000	$ 1,097,868,000