Annual report pursuant to Section 13 and 15(d)

Available-for-Sale Securities, at Fair Value (Details)

v2.4.0.8
Available-for-Sale Securities, at Fair Value (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, at fair value $ 12,256,727 $ 13,666,954
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, at fair value 2,977,291 3,608,272
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, at fair value 4,435,820 5,130,965
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, at fair value 2,084,298 2,272,866
Mortgage-backed Securities, Issued by Private Enterprises [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, at fair value $ 2,759,318 $ 2,654,851