Quarterly report pursuant to Section 13 or 15(d)

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

v3.2.0.727
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Jun. 30, 2015
Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments $ 44,952 $ (116,019) $ (81,491) $ (221,547)
Derivative Instruments, Gain (Loss) Recognized in Income, Net (5,484) (24,202) (2,517) (18,401)
Gain (Loss) on Interest Rate Swap and Swaption Agreements     35,258 (182,420)
Gain (Loss) on Mortgage Loans Held-for-Sale (6,832) 11,801 2,260 8,620
Trading Activity, Gains and Losses, Net 34,338 (136,058) (88,168) (236,202)
Agency To-be-Announced Securities, Non-Risk Management [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net 0 0 0 (4,701)
Inverse Interest-Only Securities [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Instruments, Gain (Loss) Recognized in Income, Net 4,909 16,052 24,170 34,375
Forward Purchase Commitments [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Gain (Loss) on Mortgage Loans Held-for-Sale (5,130) 4,163 (4,160) 3,746
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 5,262 (29,877) (22,696) (47,780)
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 125 (8) 125 (8)
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 5,671 (4,614) 8,206 (6,319)
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 (837) 0 (837) 0
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 74 (6,103) 6,164 5,428
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 19,752 (57,250) 1,246 (169,808)
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 (20,658) 353 (17,526) (1,372)
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 (42,470) 65,963 (144) 106,942
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 20,713 (46,341) (31,846) (59,761)
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 46,957 (78,391) (50,747) (98,920)
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 $ (30) $ (5) $ (123) $ 1,976