Real Estate And Accumulated Depreciation (Changes In Accumulated Depreciation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at beginning of year	$ 1,059,531	$ 971,249	$ 856,281
Additions at cost	130,965	133,220	127,238
Retirements or sales	(157,723)	(23,418)	(12,270)
Property held for sale	0	(21,520)	0
Property transferred from held for sale (see Note 15)	8,066	0	0
Balance at end of year	$ 1,040,839	$ 1,059,531	$ 971,249