Financial Highlights (Expense Ratios To Average Equity) (Details)	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Financial Highlights [Abstract]
Operating expenses before incentive fee, interest expense, and other investment related expenses	(3.03%)	[1],[2]	(2.67%)	[1],[2]	(2.86%)	[1],[2]	(2.77%)	[1],[2]
Ratio Of Incentive Fee To Average Equity	(0.21%)	[1],[2]	(0.32%)	[1],[2]	(0.22%)	[1],[2]	(0.91%)	[1],[2]
Interest expense and other investment related expenses	(1.98%)	[1],[2]	(2.11%)	[1],[2]	(2.08%)	[1],[2]	(1.94%)	[1],[2]
Total Expenses	(5.22%)	[1],[2]	(5.10%)	[1],[2]	(5.16%)	[1],[2]	(5.62%)	[1],[2]

[1] Average equity is calculated using month end values.

[2] Ratios are annualized except for the incentive fee which is not annualized.