Consolidated Statement Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 52,451	$ 42,823
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	(11,450)	(46,109)
Net realized (gain) loss on investments and financial derivatives	(18,264)	23,068
Amortization of premiums and accretion of discounts (net)	(10,204)	(5,150)
Purchase of investments	(1,026,018)	(1,188,608)
Proceeds from disposition of investments	602,098	1,257,719
Proceeds from principal payments of investments	97,641	63,097
Proceeds from investments sold short	631,565	480,034
Repurchase of investments sold short	(624,288)	(459,870)
Payments made to open financial derivatives	(4,974)	(67,208)
Proceeds received to close financial derivatives	23,201	89,373
Proceeds received to open financial derivatives	11,815	35,603
Payments made to close financial derivatives	(14,934)	(38,363)
Shares issued in connection with incentive fee payment	941	0
Share-based LTIP expense	85	58
(Increase) decrease in assets:
Increase in repurchase agreements	(27,538)	(20,998)
Increase in receivable for securities sold	(45,116)	(78,158)
(Increase) decrease in due from brokers	(25,550)	4,803
Increase in interest and principal receivable	(852)	(1,002)
Increase in other assets	(674)	(626)
Increase (decrease) in liabilities:
Decrease in due to brokers	(609)	(33,350)
Increase (decrease) in payable for securities purchased	78,751	(44,217)
Increase (decrease) in accounts payable and accrued expenses	(159)	278
Increase (decrease) in incentive fee payable	(6,161)	2,312
Increase (decrease) in other payables	(592)	0
Increase (decrease) in interest and dividends payable	948	(224)
Increase in base management fee payable	471	101
Net cash provided by (used in) operating activities	(317,416)	15,386
Cash flows provided by (used in) financing activities:
Proceeds from the issuance of shares	125,600	0
Proceeds from Noncontrolling Interests	4,664	0
Offering costs paid	(253)	0
Dividends paid	(51,976)	(18,522)
Proceeds from issuance of securitized debt	0	1,522
Principal payments on securitized debt	(182)	(115)
Reverse repurchase agreements, net of repayments	382,274	(12,888)
Net cash provided by (used in) financing activities	460,127	(30,003)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	142,711	(14,617)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	59,084	62,737
CASH AND CASH EQUIVALENTS, END OF PERIOD	201,795	48,120
Supplemental disclosure of cash flow information:
Interest paid	4,007	4,034
Shares issued in connection with incentive fee payment (non-cash)	941	0
Share-based LTIP awards (non-cash)	85	58
Aggregate TBA trade activity (buys sells) (non-cash)	$ 10,009,367	$ 8,312,761