Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Put and Call Options for TBAs (Details)

v3.4.0.3
Derivative Instruments and Hedging Activities Put and Call Options for TBAs (Details) - USD ($)
$ in Thousands
Mar. 31, 2016
Dec. 31, 2015
Mar. 31, 2015
Dec. 31, 2014
Derivative [Line Items]        
Derivative, Notional Amount $ 26,390,596 $ 21,998,381 $ 33,709,043 $ 48,115,523
Options Held [Member]        
Derivative [Line Items]        
Derivative, Notional Amount 2,000,000 0 $ 2,500,000 $ 2,000,000
Derivative, Cost (1,300)      
Derivative Financial Instruments, Liabilities [Member]        
Derivative [Line Items]        
Derivative, Notional Amount 9,621,098 1,362,384    
Derivative, Fair Value, Net (77,038) (7,285)    
Derivative Financial Instruments, Liabilities [Member] | Options Held [Member]        
Derivative [Line Items]        
Derivative, Notional Amount 0      
Derivative, Fair Value, Net 0      
Derivative Financial Instruments, Assets [Member]        
Derivative [Line Items]        
Derivative, Notional Amount 17,869,498 21,735,997    
Derivative, Fair Value, Net 197,847 $ 271,509    
Derivative Financial Instruments, Assets [Member] | Options Held [Member]        
Derivative [Line Items]        
Derivative, Notional Amount 2,000,000      
Derivative, Fair Value, Net $ 366