Net Gains (Losses) on Sales of Properties and Discontinued Operations (Schedule Of Gains, Losses, And Impairment Losses For Continuing And Discontinued Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Gains (Losses) on Sales of Properties and Discontinued Operations [Abstract]
Continuing Operations, Gain from sale of office building									$ 0	$ 0	$ 1,129
Continuing Operations, Impairment losses	(2,495)	(164)	(7)	0	(364)	0	(2,735)	266	(2,666)	(2,833)	(4,523)
Continuing Operations, Gain (loss) on sale of assets									(47)	3	4
Gain, losses and impairment losses for continuing operation									(2,713)	(2,830)	(3,390)
Discontinued Operations, Gain from sales of properties									1,892	7,872	376
Discontinued Operations, Impairment losses									(4,420)	(7,339)	(9,785)
Discontinued Operations, Loss on sale of assets									(39)	(42)	(57)
Gain, losses and impairment losses for discontinued operation									(2,567)	491	(9,466)
Gains, losses and impairment losses for continuing and discontinued operations									$ (5,280)	$ (2,339)	$ (12,856)