Financial Highlights (Results Of Operations For A Share Outstanding) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Dec. 31, 2012	Dec. 31, 2011
Increase (Decrease) Earnings Per Share [Roll Forward]
Beginning Shareholders' Equity Per Share (12/31/2012 and 12/31/2011, respectively)	$ 24.86		$ 22.55
Net Investment Income	$ 0.52		$ 0.67
Net Realized/Unrealized Gains (Losses)	$ 1.48		$ 1.28
Results of Operations Attributable to Equity	$ 2.00		$ 1.95
NetIncomeLossAttributableToNoncontrollingInterestPerShare	$ (0.02)		$ 0.00
NetIncomeLossAttributableToParentPerShare	$ 1.98	[1]	$ 1.95	[1]
Dividends Paid Per Common Share	$ (1.52)		$ (0.40)
Weighted Average Share Impact on Dividends Paid (2)	$ (0.05)	[2]	$ (0.01)	[2]
Accretive (Dilutive) Effect of Share Issuances (Net of Offering Costs) and Share Repurchases	$ 0.01		$ 0.00
Ending Shareholders' Equity Per Share (3/31/2013 and 3/31/2012, respectively)(3)	$ 25.28	[3]	$ 24.09	[3]
Shares Outstanding, end of period	20,403,723		16,447,651		20,370,469	16,447,651
Shareholders Equity Per Share Upon Conversion Of All Convertible Units (in usd per share)	$ 24.78
Shareholders' equity per share upon conversion of LTIPs (in usd per share)			$ 23.53		$ 24.38

[1] Calculated based on average common shares outstanding and can differ from the calculation for EPS (See Note 9).

[2] Per share impact on dividends paid relating to share issuances/repurchases during the period as well as dividends paid to LTIP and OP unit holders.

[3] If all LTIP units and OP units (if applicable) previously issued were vested and exchanged for common shares as of March 31, 2013 and 2012, shareholders' equity per share would be $24.78 and $23.53, respectively.