Description Of Business And Segment Reporting (Reconciliation To Net Income Attributable To Common Shareholders) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Segment operating income (loss)	$ (12,532)	$ (22,195)	$ (26,510)	$ (29,235)
Depreciation and amortization expense	(5,801)	(5,266)	(11,451)	(10,537)
General and administrative expense	(8,834)	(5,102)	(13,931)	(11,047)
Equity earnings of unconsolidated joint ventures	283	(274)	233	(195)
Gain (loss) on sale of assets	43,241		89,786
Other income (expense)	154	19	1,795	(196)
Income (loss) before income taxes	28,141	(24,454)	57,936	(33,423)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment operating income (loss)	(8,399)	(18,061)	(18,044)	(20,528)
Unallocated Corporate Expense [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	(387)	(227)	(618)	(419)
General and administrative expense	(3,746)	(3,907)	(7,848)	(8,288)
Interest expense, net	$ (3,005)	$ (2,004)	$ (7,368)	$ (3,797)