Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Interest income:
Interest income on mortgage-backed securities	$ 128,720	$ 113,188	$ 241,480	$ 200,123
Interest income on short-term cash investments	441	331	773	671
Interest income	129,161	113,519	242,253	200,794
Interest expense	46,169	35,910	87,278	62,104
Net interest income	82,992	77,609	154,975	138,690
Operating expenses:
Management fee	4,312	3,531	8,154	6,623
Share based compensation	425	194	854	401
General and administrative	1,316	746	2,229	1,305
Total operating expenses	6,053	4,471	11,237	8,329
Other income:
Gain on sale of mortgage-backed securities	12,205	4,405	14,710	4,405
Net income	$ 89,144	$ 77,543	$ 158,448	$ 134,766
Earnings per share - common stock, basic	$ 0.91	$ 1.04	$ 1.80	$ 2.01
Earnings per share - common stock, diluted	$ 0.91	$ 1.04	$ 1.80	$ 2.01
Dividends per share	$ 0.90	$ 1.00	$ 1.80	$ 2.00
Weighted average shares outstanding	97,969,074	74,807,174	87,789,596	67,167,275