Description Of Business And Segment Reporting (Reconciliation To Net Income Attributable To Common Shareholders) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Segment operating income (loss)	$ (10,951)	$ (17,375)	$ (37,461)	$ (46,610)
Depreciation and amortization expense	(5,560)	(5,612)	(17,011)	(16,149)
General and administrative expense	(5,274)	(4,228)	(19,205)	(15,275)
Equity earnings of unconsolidated joint ventures	(75)	(97)	158	(292)
Gain (loss) on sale of assets	2,559	(1)	92,345	(1)
Other income (expense)	440	10	2,236	(186)
Income (loss) before income taxes	(11,095)	(19,842)	46,841	(53,265)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment operating income (loss)	(6,542)	(14,254)	(24,587)	(34,782)
Unallocated Corporate Expense [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	(300)	(215)	(917)	(634)
General and administrative expense	(4,109)	(2,906)	(11,957)	(11,194)
Interest expense, net	$ (3,068)	$ (2,379)	$ (10,437)	$ (6,176)