Income Taxes (Schedule of Per Share Distributions Reported to Shareholders) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Ordinary Income	$ 0.96	$ 1.08	$ 0.89
Long-term capital gain	$ 0.64	$ 0.13	$ 0.20
Unrecaptured Sec. 1250 gain	$ 0.64	$ 0.23	$ 0.48
Return of capital	$ 0.00	$ 0.52	$ 0.23
Total common share distributions	$ 2.24	$ 1.96	$ 1.80
Percentage Of Distributions Representing Tax Preference Items	5.72%	2.83%	3.91%