Consolidated Statement Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 64,274	$ 72,360
Reconciliation of the net increase in equity resulting from operations to net cash provided by (used in) operating activities:
Change in net unrealized gain (loss) on investments and financial derivatives	(4,578)	(69,972)
Net realized (gain) loss on investments and financial derivatives	(22,552)	18,126
Amortization of premiums and accretion of discounts (net)	(15,485)	(8,904)
Purchase of investments	(1,763,022)	(1,763,718)
Proceeds from disposition of investments	1,166,380	1,802,659
Proceeds from principal payments of investments	145,570	103,733
Proceeds from investments sold short	905,142	576,851
Repurchase of investments sold short	(652,073)	(600,777)
Payments made to open financial derivatives	(11,720)	(78,043)
Proceeds received to close financial derivatives	35,406	111,235
Proceeds received to open financial derivatives	27,986	40,248
Payments made to close financial derivatives	(26,686)	(53,439)
Shares issued in connection with incentive fee payment	1,058	231
Share-based LTIP expense	129	89
(Increase) decrease in assets:
(Increase) decrease in repurchase agreements	(27,344)	1,970
(Increase) decrease in receivable for securities sold	(299,719)	9,175
(Increase) decrease in due from brokers	(42,415)	8,969
Increase in interest and principal receivable	(972)	(460)
Increase in other assets	(713)	(229)
Increase (decrease) in liabilities:
Decrease in due to brokers	(17,214)	(45,171)
Increase in payable for securities purchased	173,317	50,936
Increase (decrease) in accounts payable and accrued expenses	262	(313)
Increase (decrease) in incentive fee payable	(5,305)	9,491
Increase (decrease) in other payables	(396)	0
Increase (decrease) in interest and dividends payable	768	(261)
Increase in base management fee payable	444	517
Net cash provided by (used in) operating activities	(369,458)	185,303
Cash flows provided by (used in) financing activities:
Proceeds from the issuance of shares	125,600	88,142
Proceeds from Noncontrolling Interests	4,664	0
Offering costs paid	(350)	(280)
Dividends paid	(72,016)	(32,766)
Proceeds from issuance of securitized debt	0	1,522
Principal payments on securitized debt	(292)	(158)
Reverse repurchase agreements, net of repayments	439,505	(235,277)
Net cash provided by (used in) financing activities	497,111	(178,817)
NET INCREASE IN CASH AND CASH EQUIVALENTS	127,653	6,486
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	59,084	62,737
CASH AND CASH EQUIVALENTS, END OF PERIOD	186,737	69,223
Supplemental disclosure of cash flow information:
Interest paid	7,217	6,009
Shares issued in connection with incentive fee payment (non-cash)	1,058	231
Share-based LTIP awards (non-cash)	129	89
Aggregate TBA trade activity (buys sells) (non-cash)	$ 16,476,137	$ 11,882,119