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
Mar. 31, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value $ 40,253  
Available-for-sale Securities, Debt Maturities, Year Two Through Three, Fair Value 170,464  
Available-for-sale Securities, Debt Maturities, Year Four Through Five, Fair Value 1,253,605  
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value 15,097,686  
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value 756,689  
Available-for-sale Securities 17,318,697 $ 13,128,857
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value 1,344  
Available-for-sale Securities, Debt Maturities, Year Two Through Three, Fair Value 49,281  
Available-for-sale Securities, Debt Maturities, Year Four Through Five, Fair Value 906,170  
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value 14,132,919  
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value 30,171  
Available-for-sale Securities 15,119,885 11,226,474
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value 38,909  
Available-for-sale Securities, Debt Maturities, Year Two Through Three, Fair Value 121,183  
Available-for-sale Securities, Debt Maturities, Year Four Through Five, Fair Value 347,435  
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value 964,767  
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value 726,518  
Available-for-sale Securities $ 2,198,812 $ 1,902,383