Financial Highlights (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Financial Highlights [Abstract]
Net asset value, beginning of period	$ 11.59		$ 13.02		$ 12.89
Net investment income	$ 2.39	[1]	$ 2.07	[1]	$ 2.55	[1]
Net gain (loss) from investments and swap and cap contracts	$ 1.27	[1]	$ (1.30)	[1]	$ 2.23	[1]
Net income	$ 3.66		$ 0.77		$ 4.78
Distributions to shareholders	$ (1.96)		$ (1.03)		$ (0.45)
Tax return of capital distributions	$ (0.29)		$ (1.27)		$ (1.49)
Issuance of common shares and amortization of share based compensation	$ 0.02	[1]	$ 0.10	[1]	$ (2.71)	[1]
Net decrease in net asset value from capital transactions	$ (2.23)		$ (2.20)		$ (4.65)
Net asset value, end of period	$ 13.02		$ 11.59		$ 13.02
Net asset total return (%)	31.75%		6.68%		16.06%
Market value total return (%)	21.22%		13.52%		24.69%	[2]
Expenses before interest expense	2.34%		2.68%		3.93%
Expenses	4.24%		3.97%		6.43%
Net investment income	19.30%		15.35%		19.09%

[1] Calculated based on average shares outstanding during the period. Average shares outstanding include vested and unvested restricted shares and differs from weighted average shares outstanding used in calculating EPS (see note 3).

[2] The market value total return was calculated for the period from June 12, 2009, the first day the Company's common stock traded on a public exchange, to December 31, 2009.