Annual report pursuant to Section 13 and 15(d)

HELD-TO-MATURITY SECURITIES - Contractual Maturities (Details)

v3.3.1.900
HELD-TO-MATURITY SECURITIES - Contractual Maturities (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Held-to-maturity Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]    
Amortized Cost $ 6,159,590 $ 3,379,905
Held-to-maturity Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]    
Held-to-maturity Securities, Fair Value 6,135,458 3,382,715
Federal agencies: Mortgage-backed    
Held-to-maturity Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]    
Held-to-maturity Securities, Under 1 year 0 0
Held-to-maturity Securities, 1-5 years 0 0
Held-to-maturity Securities, 6-10 years 25,909 24,901
Held-to-maturity Securities, Over 10 years 5,506,592 3,136,460
Amortized Cost 5,532,501 3,161,361
Held-to-maturity Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]    
Fair Value, Under 1 year 0 0
Fair Value, 1-5 years 0 0
Fair Value, 6-10 years 25,227 24,263
Fair Value, Over 10 Years 5,484,407 3,140,194
Held-to-maturity Securities, Fair Value 5,509,634 3,164,457
Federal agencies: Other agencies    
Held-to-maturity Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]    
Held-to-maturity Securities, Under 1 year 0 0
Held-to-maturity Securities, 1-5 years 0 0
Held-to-maturity Securities, 6-10 years 283,960 54,010
Held-to-maturity Securities, Over 10 years 336,092 156,553
Amortized Cost 620,052 210,563
Held-to-maturity Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]    
Fair Value, Under 1 year 0 0
Fair Value, 1-5 years 0 0
Fair Value, 6-10 years 284,907 54,843
Fair Value, Over 10 Years 334,004 155,821
Held-to-maturity Securities, Fair Value 618,911 210,664
Total U.S. Government backed agencies    
Held-to-maturity Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]    
Amortized Cost 6,152,553 3,371,924
Held-to-maturity Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]    
Held-to-maturity Securities, Fair Value 6,128,545 3,375,121
Municipal securities    
Held-to-maturity Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]    
Held-to-maturity Securities, Under 1 year 0 0
Held-to-maturity Securities, 1-5 years 0 0
Held-to-maturity Securities, 6-10 years 0 0
Held-to-maturity Securities, Over 10 years 7,037 7,981
Amortized Cost 7,037 7,981
Held-to-maturity Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]    
Fair Value, Under 1 year 0 0
Fair Value, 1-5 years 0 0
Fair Value, 6-10 years 0 0
Fair Value, Over 10 Years 6,913 7,594
Held-to-maturity Securities, Fair Value $ 6,913 $ 7,594