Consolidated Statement Of Assets, Liabilities And Equity (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Investments at value, cost	$ 1,902,651	$ 2,122,326
Financial derivatives–assets, at fair value Net cost	78,599	61,560
Repurchase agreements, cost	45,073	172,001
Investments sold short at value, proceeds	(1,193,569)	(1,290,091)
Financial derivatives-liabilities, at fair value Net proceeds	(37,184)	(33,555)
Securitized debt proceeds	$ (663)	$ (749)
Common stock, par value
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	33,449,678	33,449,678
Common stock, shares outstanding	33,449,678	33,449,678