Quarterly report pursuant to Section 13 or 15(d)

Available-for-Sale Securities, Weighted Average Life Classifications (Details)

v3.7.0.1
Available-for-Sale Securities, Weighted Average Life Classifications (Details) - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Less than or equal to 1 year $ 41,447  
Greater than 1 year and less than or equal to 3 years 243,270  
Greater than 3 years and less than or equal to 5 years 2,439,495  
Greater than 5 years and less than or equal to 10 years 12,862,728  
Greater than 10 years 840,770  
Available-for-sale securities, at fair value 16,427,710 $ 13,128,857
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less than or equal to 1 year 557  
Greater than 1 year and less than or equal to 3 years 48,271  
Greater than 3 years and less than or equal to 5 years 2,127,292  
Greater than 5 years and less than or equal to 10 years 11,973,466  
Greater than 10 years 21,682  
Available-for-sale securities, at fair value 14,171,268 11,226,474
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less than or equal to 1 year 40,890  
Greater than 1 year and less than or equal to 3 years 194,999  
Greater than 3 years and less than or equal to 5 years 312,203  
Greater than 5 years and less than or equal to 10 years 889,262  
Greater than 10 years 819,088  
Available-for-sale securities, at fair value $ 2,256,442 $ 1,902,383