CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income	$ 108,325	$ 140,820	$ 126,487
Noncash items
Amortization of investment premiums	121,190	101,872	125,872
Amortization of equity-based awards	2,132	2,390	2,201
Other depreciation and amortization	109	137	162
Change in measureable hedge ineffectiveness related to interest rate swap agreements designated as cash flow hedges	(162)	76	(168)
Net change in receivables, other assets, accounts payable and accrued expenses	12,651	3,517	6,658
Net cash provided by operating activities	244,245	248,812	261,212
Investing activities
Purchases of residential mortgage investments	(3,887,051)	(3,307,963)	(3,326,345)
Interest receivable acquired with the purchase of residential mortgage investments	(5,494)	(5,313)	(5,559)
Principal collections on residential mortgage investments, including changes in mortgage securities principal remittance receivable	3,419,867	2,785,337	3,516,634
Investment in Federal Home Loan Bank stock	(60,002)	0	0
Net cash (used in) provided by investing activities	(532,680)	(527,939)	184,730
Financing activities
Proceeds from repurchase arrangements and similar borrowings	111,006,967	128,594,880	136,909,245
Principal payments on repurchase arrangements and similar borrowings	(113,730,416)	(128,270,935)	(137,210,576)
Proceeds from other secured borrowings	5,425,000	0	0
Principal payments on other secured borrowings	(2,550,000)	0	0
Decrease (increase) in cash collateral receivable from interest rate swap counterparties	2,946	(27,637)	24,470
Cash paid to redeem convertible preferred shares	0	0	(207,033)
Common stock repurchases	0	0	(7,292)
Proceeds from issuance of preferred shares	13,266	18,180	165,756
Other capital stock transactions	(429)	(468)	(410)
Dividends paid	(132,240)	(140,723)	(132,191)
Net cash provided by (used in) financing activities	35,094	173,297	(458,031)
Net change in cash and cash equivalents	(253,341)	(105,830)	(12,089)
Cash and cash equivalents at beginning of year	307,526	413,356	425,445
Cash and cash equivalents at end of year	$ 54,185	$ 307,526	$ 413,356