CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)
$ in Thousands
 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Operating activities :    
Net income $ 65,423 $ 79,968
Noncash items:    
Amortization of investment premiums 95,139 92,458
Amortization of equity-based awards 1,241 1,708
Other depreciation and amortization 97 100
Change in measureable hedge ineffectiveness related to interest rate swap agreements designated as cash flow hedges 506 130
Net change in receivables, other assets, accounts payable and accrued expenses (953) 6,389
Net cash provided by operating activities 161,453 180,753
Investing activities:    
Purchases of residential mortgage investments (2,319,819) (2,757,199)
Interest receivable acquired with the purchase of residential mortgage investments (3,139) (4,202)
Principal collections on residential mortgage investments, including changes in mortgage securities principal remittance receivable 2,773,344 2,577,985
Decrease (increase) in lending counterparty investments 50,000 (46,002)
Net cash provided by (used in) investing activities 500,386 (229,418)
Financing activities:    
Proceeds from repurchase arrangements and similar borrowings 94,430,910 84,927,006
Principal payments on repurchase arrangements and similar borrowings (92,332,463) (87,281,325)
Proceeds from other secured borrowings 1,175,000 2,450,000
Principal payments on other secured borrowings (3,800,000) (150,000)
Increase in cash collateral receivable from interest rate swap counterparties (22,998) (12,729)
Proceeds from issuance of preferred shares 1,167 12,679
Other capital stock transactions (57) (429)
Dividends paid (83,886) (103,561)
Net cash used in financing activities (632,327) (158,359)
Net change in cash and cash equivalents 29,512 (207,024)
Cash and cash equivalents at beginning of period 54,185 307,526
Cash and cash equivalents at end of period $ 83,697 $ 100,502