Summary Of Significant Accounting Policies (Schedule Of Financial Instruments Having Difference Between Carrying Amount And Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Summary Of Significant Accounting Policies [Abstract]
Investment in direct financing lease, Carrying Amount	$ 10,798	$ 12,185
Investment in direct financing lease, Fair Value	12,613	14,439
Note receivable from APM, Carrying Amount	4,749	4,880
Note receivable from APM, Fair Value	7,825	7,970
Debt, Carrying Amount	(1,245,014)	(1,156,568)
Debt, Fair Value	$ (1,302,550)	$ (1,206,347)