Financial Highlights (Results Of Operations For A Share Outstanding) (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011		Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Financial Highlights [Abstract]
Beginning Shareholders' Equity Per Share	$ 24.09		$ 23.80		$ 22.55		$ 24.47
Net Investment Income	$ 0.54		$ 0.73		$ 1.20		$ 1.37
Net Realized/Unrealized Gains (Losses)	$ 0.12		$ (0.81)		$ 1.41		$ (0.78)
Results of Operations	$ 0.66	[1]	$ (0.08)	[1]	$ 2.61	[1]	$ 0.59	[1]
Dividends Paid	$ (0.72)	[2]	$ (0.41)	[2]	$ (1.13)	[2]	$ (1.75)	[2]
Ending Shareholders' Equity Per Share	$ 24.03	[3]	$ 23.31	[3]	$ 24.03	[3]	$ 23.31	[3]
Shares Outstanding, end of period	16,447,651		16,507,381		16,447,651		16,507,381		16,447,651	16,447,651	16,504,742	16,498,342
Dividend declared and paid per common share and LTIP units	$ 0.70		$ 0.40		$ 1.10		$ 1.71
Shareholders' equity per share upon conversion	$ 23.47		$ 22.78		$ 23.47		$ 22.78			$ 22.03

[1] Calculated based on average common shares outstanding and can differ from the calculation for EPS (See Note 8).

[2] Dividends paid include dividends paid on common shares and LTIP units. For the three month periods ending June 30, 2012 and 2011, dividends totaling $0.70 and $0.40, respectively, per common share and LTIP unit outstanding were declared and paid. For the six month periods ending June 30, 2012 and 2011, two dividends totaling $1.10 and $1.71, respectively, per common share and LTIP unit outstanding were declared and paid. Dividends paid of $0.72 and $0.41 per share for the three month periods ending June 30, 2012 and 2011, respectively, and dividends paid of $1.13 and $1.75 per share for the six month periods ending June 30, 2012 and 2011, respectively, above reflect the impact of dividing the total dividend payment, inclusive of LTIP units, by average common shares outstanding, exclusive of LTIP units.

[3] If all LTIP units previously issued were vested and exchanged for common shares as of June 30, 2012 and 2011, shareholders' equity per share would be $23.47 and $22.78, respectively.