Description Of Business And Segment Reporting (Reconciliation To Net Income Attributable To Common Shareholders) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Segment operating income (loss)	$ (61,313)	$ 9,123	$ 23,624
Depreciation and amortization expense	(22,317)	(22,747)	(22,275)
General and administrative expense	(16,998)	(25,395)	(27,337)
Equity earnings (loss) of unconsolidated joint ventures	(449)	792	974
(Loss) gain on sale of assets	(1)	(2)	(41)
Other (expense) income	293	325	(256)
Income (loss) before income taxes	(70,824)	2,334	17,464
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment operating income (loss)	(47,519)	28,470	45,305
Depreciation and amortization expense	(21,347)	(22,333)	(21,881)
Unallocated Corporate Expense [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	(970)	(414)	(394)
General and administrative expense	(12,824)	(18,933)	(21,287)
Interest expense, net	(9,354)	(7,904)	(6,837)
Equity earnings (loss) of unconsolidated joint ventures	(449)	792	974
(Loss) gain on sale of assets	(1)	(2)	(41)
Other (expense) income	293	325	(256)
Income (loss) before income taxes	$ (70,824)	$ 2,334	$ 17,464