Consolidated Statement Of Assets, Liabilities And Equity (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Investments at value, cost	$ 2,122,326	$ 1,688,257
Financial derivatives–assets, at fair value Net cost	61,560	50,533
Repurchase agreements, cost	172,001	27,943
Investments sold short at value, proceeds	(1,290,091)	(847,602)
Financial derivatives-liabilities, at fair value Net proceeds	(33,555)	(29,746)
Securitized debt proceeds	$ (749)	$ (980)
Common stock, par value
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	33,449,678	25,428,186
Common stock, shares outstanding	33,449,678	25,428,186