Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities:
Net income	$ 51,136	$ 35,323
Adjustments to reconcile net income to cash provided by operating activities:
Increase in accrued interest receivable	(1,231)	(5,009)
Decrease in accrued interest payable	(1,234)	(174)
Provision for loan losses	261	60
Gain on sale of investments, net	(3,422)	(2,938)
Fair value adjustments, net	(10,596)	93
Amortization and depreciation	66,751	33,012
Stock-based compensation expense	1,115	920
Cash paid for stock appreciation rights	(9)	(21)
Net change in other assets and other liabilities	(782)	(2,139)
Net cash and cash equivalents provided by operating activities	101,989	59,127
Investing activities:
Purchase of investments	(1,310,794)	(1,517,541)
Principal payments received on investments	486,924	269,642
(Increase) decrease in principal receivable on investments	(5,852)	(2,766)
Proceeds from sales of investments	164,916	106,206
Principal payments received on securitized mortgage loans	8,495	16,408
Net payments on derivatives not designated as hedges	(436)	(342)
Other investing activities	142	(1,707)
Net cash and cash equivalents used in investing activities	(656,605)	(1,130,100)
Financing activities:
Borrowings under repurchase agreements, net	507,056	1,018,131
Principal payments on non-recourse collateralized financing	(5,940)	(39,455)
Proceeds from issuance of preferred stock	54,251	0
Proceeds from issuance of common stock	7,412	123,808
Payments Related to Tax Withholding for Share-based Compensation	(545)	0
Dividends paid	(34,084)	(26,524)
Net cash and cash equivalents provided by financing activities	528,150	1,075,960
Net increase in cash and cash equivalents	(26,466)	4,987
Cash and cash equivalents at beginning of period	55,809	48,776
Cash and cash equivalents at end of period	29,343	53,763
Supplemental Disclosure of Cash Activities:
Cash paid for interest	$ 22,065	$ 15,314