Income Taxes (Income Tax Characterization Of Dividends) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Income Taxes [Abstract]
Capital gains, Amount					$ 0.51	[1]
Unrecaptured Section 1250 gains, Amount					$ 0.04	[1]
Ordinary income, Amount	$ 0.23	[1]
Return of capital, Amount	$ 0.59	[1]	$ 0.80	[1]	$ 0.25	[1]
Dividends paid per common share	$ 0.82	[1]	$ 0.80	[1]	$ 0.80	[1]
Percentage of Capital gains					63.20%	[1]
Percentage of Unrecaptured Section 1250 gains					5.30%	[1]
Percentage of Ordinary income	28.00%	[1]
Percentage of Return of capital	72.00%	[1]	100.00%	[1]	31.50%	[1]
Percentage of dividend paid per common share	100.00%	[1]	100.00%	[1]	100.00%	[1]

[1] The amounts and percentages detailed in the table above represent average amounts for the years presented. Actual quarterly amounts may differ.