Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Agency securities pledged	$ 10,208,822	$ 12,109,868
Non-Agency securities pledged	$ 269,855	$ 0
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares issued (in shares)	36,692,000	36,682,000
Common stock, shares outstanding (in shares)	36,692,000	36,682,000
Series A Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	9,610,000
Preferred stock, dividend rate	8.25%	8.25%
Preferred stock, shares issued (in shares)	2,181,000	2,181,000
Preferred stock, shares outstanding (in shares)	2,181,000	2,181,000
Preferred stock, aggregate liquidation preference	$ 54,514	$ 54,514
Series B Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	6,210,000
Preferred stock, dividend rate	7.875%	7.875%
Preferred stock, shares issued (in shares)	5,650,000	5,650,000
Preferred stock, shares outstanding (in shares)	5,650,000	5,650,000
Preferred stock, aggregate liquidation preference	$ 141,250	$ 141,250