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Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance (Details)

v3.5.0.2
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments $ 5,584 $ (171,656) $ (132,608) $ (253,147)
Derivative Instruments, Gain (Loss) Recognized in Income, Net (12,028) (455) (44,064) (2,972)
Gain (Loss) on Mortgage Loans Held-for-Sale (889) 16,040 17,648 18,300
Trading Activity, Gains and Losses, Net (6,337) (169,277) (174,217) (257,446)
Inverse Interest-Only Securities [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net 1,288 9,926 22,003 34,096
Loan Purchase Commitments [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Mortgage Loans Held-for-Sale 107 2,834 2,455 (1,327)
Interest Rate Risk Associated with the Investment Portfolio [Member] | Forward Contracts [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net (522) (2,982) 26,369 (25,677)
Interest Rate Risk Associated with the Investment Portfolio [Member] | Short US Treasury Securities [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net 0 0 0 125
Interest Rate Risk Associated with the Investment Portfolio [Member] | Options Held [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net (6,226) (1,358) (51,259) 6,848
Interest Rate Risk Associated with the Investment Portfolio [Member] | Treasury Lock [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net 0 0 0 (837)
Interest Rate Risk Associated with the Investment Portfolio [Member] | Swap [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net 0 0 0 6,164
Interest Rate Risk Associated with the Investment Portfolio [Member] | Interest Rate Swaption [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments (24,394) (66,809) (18,397) (65,563)
Interest Rate Risk Associated with the Investment Portfolio [Member] | Total Return Swap [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net (6,550) (5,966) (41,541) (23,492)
Interest Rate Risk Associated with the Investment Portfolio [Member] | Short [Member] | Interest Rate Swap [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments (18,381) 86,672 131,465 86,528
Interest Rate Risk Associated with the Investment Portfolio [Member] | Long [Member] | Interest Rate Swap [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments 22,973 (70,546) (89,043) (102,392)
Interest Rate Risk Associated with Borrowings [Member] | Long [Member] | Interest Rate Swap [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments 25,386 (120,973) (156,633) (171,720)
Credit Risk Associated with Non-Agency RMBS and Mortgage Loans Held-for-Sale [Member] | Credit Default Swap, Selling Protection [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net $ (18) $ (75) $ 364 $ (199)