CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating activities:
Net income	$ 38,391	$ 34,918
Noncash items:
Amortization of investment premiums	22,288	28,399
Depreciation and other amortization	37	47
Amortization of equity-based awards	718	512
Change in measureable hedge ineffectiveness related to interest rate swap agreements designated as cash flow hedges	0	(138)
Net change in receivables, other assets, accounts payable and accrued expenses	(37)	(499)
Net cash provided by operating activities	61,397	63,239
Investing activities:
Purchases of residential mortgage investments	(669,003)	(839,897)
Interest receivable acquired with the purchase of residential mortgage investments	(1,121)	(1,495)
Principal collections on residential mortgage investments, including changes in mortgage securities principal remittance receivable	617,074	819,023
Net cash used in investing activities	(53,050)	(22,369)
Financing activities:
Proceeds from repurchase arrangements and similar borrowings	31,981,126	34,947,671
Principal payments on repurchase arrangements and similar borrowings	(31,873,771)	(34,910,386)
(Increase) decrease in cash collateral receivable from interest rate swap counterparties	(10,494)	9,739
Common share repurchases	0	(7,292)
Proceeds from issuance of preferred shares	1,336	0
Other capital stock transactions	(512)	(521)
Dividends paid	(33,095)	(34,016)
Net cash provided by financing activities	64,590	5,195
Net change in cash and cash equivalents	72,937	46,065
Cash and cash equivalents at beginning of period	413,356	425,445
Cash and cash equivalents at end of period	$ 486,293	$ 471,510