Quarterly report pursuant to Section 13 or 15(d)

Available-for-sale Securities Classified by Rate Type (Details)

v2.4.0.8
Available-for-sale Securities Classified by Rate Type (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, at fair value $ 12,634,056 $ 12,256,727
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Adjustable Rate 944,503 1,006,621
Available-for-sale Securities, Fixed Rate 8,879,422 8,490,788
Available-for-sale securities, at fair value 9,823,925 9,497,409
Mortgage-backed Securities, Issued by Private Enterprises [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Adjustable Rate 2,449,928 2,403,078
Available-for-sale Securities, Fixed Rate 360,203 356,240
Available-for-sale securities, at fair value 2,810,131 2,759,318
Collateralized Mortgage Backed Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Adjustable Rate 3,394,431 3,409,699
Available-for-sale Securities, Fixed Rate 9,239,625 8,847,028
Available-for-sale securities, at fair value $ 12,634,056 $ 12,256,727