Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities:
Net income	$ 35,323	$ 23,874
Adjustments to reconcile net income to cash provided by operating activities:
Increase in accrued interest receivable	(5,009)	(5,275)
(Decrease) increase in accrued interest payable	(174)	358
Provision for loan losses	60	450
Gain on sale of investments, net	(2,938)	(742)
Fair value adjustments, net	93	(5)
Amortization and depreciation	33,012	11,427
Stock-based compensation expense	920	353
Cash paid for stock appreciation rights	(21)	0
Net change in other assets and other liabilities	(2,481)	2,840
Net cash and cash equivalents provided by operating activities	58,785	33,280
Investing activities:
Purchase of investments	(1,517,541)	(1,244,687)
Principal payments received on investments	269,642	207,014
Increase in principal receivable on investments	(2,766)	(10,663)
Proceeds from sales of investments	106,206	35,351
Principal payments received on securitized mortgage loans	16,408	21,417
Other investing activities	(1,707)	(204)
Net cash and cash equivalents used in investing activities	(1,129,758)	(991,772)
Financing activities:
Borrowings under repurchase agreements, net	1,018,131	899,066
Principal payments on non-recourse collateralized financing	(39,455)	(1,600)
Proceeds from issuance of common stock	123,808	95,242
Dividends paid	(26,524)	(19,077)
Net cash and cash equivalents provided by financing activities	1,075,960	973,631
Net increase in cash and cash equivalents	4,987	15,139
Cash and cash equivalents at beginning of period	48,776	18,836
Cash and cash equivalents at end of period	53,763	33,975
Supplemental Disclosure of Cash Activities:
Cash paid for interest	$ 15,314	$ 9,881