Consolidated Statement Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 40,746	$ 32,055
Reconciliation of the net increase in equity resulting from operations to net cash provided by (used in) operating activities:
Change in net unrealized gain on investments and financial derivatives	(17,585)	(32,884)
Net realized (gain) loss on investments and financial derivatives	(12,592)	11,789
Amortization of premiums and accretion of discounts (net)	(4,596)	(2,346)
Purchase of investments	(448,079)	(827,052)
Proceeds from disposition of investments	280,923	814,756
Proceeds from principal payments of investments	46,326	29,722
Proceeds from investments sold short	662,132	566,348
Repurchase of investments sold short	(633,283)	(450,793)
Payments made to open financial derivatives	(732)	(40,628)
Proceeds received to close financial derivatives	10,766	41,907
Proceeds received to open financial derivatives	5,165	21,564
Payments made to close financial derivatives	(6,327)	(18,952)
Shares issued in connection with incentive fee payment	734	0
Share-based LTIP expense	42	28
(Increase) decrease in assets:
(Increase) decrease in repurchase agreements	(28,964)	2,100
(Increase) decrease in receivable for securities sold	17,680	(108,510)
Decrease in deposits with dealers held as collateral	767	1,801
(Increase) decrease in interest and principal receivable	212	(11)
Increase in other assets	(29)	(828)
Increase (decrease) in liabilities:
Decrease in due to brokers on margin accounts	(9,355)	(14,238)
Increase (decrease) in payable for securities purchased	75,417	(56,829)
Decrease in accounts payable and accrued expenses	(64)	(323)
Increase (decrease) in incentive fee payable	(5,288)	0
Increase (decrease) in other payables	(903)	0
Increase in interest and dividends payable	317	94
Increase in base management fee payable	33	96
Net cash used in operating activities	(26,537)	(31,134)
Cash flows provided by financing activities:
Proceeds from Noncontrolling Interests	4,664	0
Offering costs paid	(3)	0
Dividends paid	(31,939)	(6,735)
Proceeds from issuance of securitized debt	0	1,522
Principal payments on securitized debt	(70)	(40)
Reverse repurchase agreements, net of repayments	59,554	25,196
Net cash provided by financing activities	32,206	19,943
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	5,669	(11,191)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	59,084	62,737
CASH AND CASH EQUIVALENTS, END OF PERIOD	64,753	51,546
Supplemental disclosure of cash flow information:
Interest paid	1,826	1,727
Shares issued in connection with incentive fee payment (non-cash)	734	0
Share-based LTIP awards (non-cash)	42	28
Aggregate TBA trade activity (buys sells) (non-cash)	$ 4,092,595	$ 4,179,427