Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Statements Of Operations [Abstract]
INVESTMENT INCOME-Interest income	$ 232,897		$ 75,539	$ 45,526
EXPENSES:
Interest	18,789		5,056	4,461
Management fees	8,442	[1]	6,088	3,633
Compensation and benefits	7,837		1,459	985
General, administrative and other	6,910		2,914	2,396
Total expenses	41,978		15,517	11,475
Net investment income	190,919		60,022	34,051
GAINS AND (LOSSES) FROM INVESTMENTS:
Net realized gain (loss) on investments	35,756		6,115	(48)
Net unrealized appreciation (depreciation) on investments	(225,660)		4,832	(39,561)
Net gain from investments	261,416		1,283	39,513
GAINS AND (LOSSES) FROM SWAP AND CAP CONTRACTS:
Net swap and cap interest income (expense)	(55,487)		(18,563)	(7,624)
Net loss on termination of swap contracts	(4,903)		(36,925)	(10,804)
Net unrealized appreciation (depreciation) on swap and cap contracts	(100,012)		16,573	8,710
Net loss from swap and cap contracts	(160,402)		(38,915)	(9,718)
NET INCOME	$ 291,933		$ 22,390	$ 63,846
NET INCOME PER COMMON SHARE:
Basic	$ 3.66		$ 0.73	$ 4.76
Diluted	$ 3.66		$ 0.73	$ 4.75

[1] For the period January 1, 2011 to August 31, 2011.