Consolidated Statement Of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS:
NET INCREASE (DECREASE) IN SHAREHOLDERS' EQUITY RESULTING FROM OPERATIONS	$ 8,626	$ 27,345
Reconciliation of the net increase (decrease) in shareholders' equity resulting from operations to net cash provided by (used in) operating activities:
Change in net unrealized (gain) loss on investments and financial derivatives	40,685	1,899
Net realized (gain) loss on investments and financial derivatives	(15,662)	(10,782)
Amortization of premiums and accretion of discounts (net)	(7,857)	(5,749)
Purchase of investments	(2,695,989)	(2,298,599)
Proceeds from disposition of investments	2,582,023	1,808,694
Proceeds from principal payments of investments	75,595	88,707
Proceeds from investments sold short	980,116	894,958
Repurchase of investments sold short	(1,226,418)	(529,748)
Payments made to open financial derivatives	(119,933)	(219,776)
Proceeds received to close financial derivatives	224,232	177,148
Proceeds received to open financial derivatives	25,878	73,352
Payments made to close financial derivatives	(27,540)	(52,642)
Shares issued in connection with incentive fee payment	203	275
Share-based LTIP expense	116	1,960
(Increase) decrease in assets:
(Increase) decrease in repurchase agreements	7,649
(Increase) decrease in receivable for securities sold	(91,287)	(512,709)
(Increase) decrease in deposits with dealers held as collateral	(16,275)	4,988
(Increase) decrease in interest and principal receivable	(1,689)	4,055
(Increase) decrease in other assets	(157)	(249)
Increase (decrease) in liabilities:
Increase (decrease) in due to brokers - margin accounts	(74,345)	(678)
Increase (decrease) in payable for securities purchased	269,450	666,149
Increase (decrease) in accounts payable and accrued expenses	(204)	1,036
Increase (decrease) in incentive fee payable	(1,422)	250
Increase (decrease) in interest and dividends payable	88	(276)
Increase (decrease) in base management fee payable	(107)	35
Net cash provided by (used in) operating activities	(64,224)	119,643
Cash flows provided by (used in) financing activities:
Shares repurchased	(309)
Offering costs paid	(469)	(1,138)
Dividends paid	(35,634)	(20,401)
Reverse repurchase agreements, net of repayments	106,456	(83,255)
Net cash provided by (used in) financing activities	70,044	(104,794)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	5,820	14,849
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	35,791	102,863
CASH AND CASH EQUIVALENTS, END OF PERIOD	41,611	117,712
Supplemental disclosure of cash flow information:
Interest paid	4,714	2,796
Shares issued in connection with incentive fee payment (non-cash)	203	275
Share-based LTIP awards (non-cash)	116	1,960
Aggregate TBA trade activity (buys + sells) (non-cash)	$ 16,291,487	$ 10,645,380