INVESTMENT SECURITIES (Details 5) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amortized Cost
Due within one year	$ 583,676
Due after one year through five years	704,674
Due after five years through ten years	464,472
Due after ten years	1,632,619
Total available-for-sale investment securities	3,385,441
Estimated Fair Value
Due within one year	565,323
Due after one year through five years	694,776
Due after five years through ten years	455,804
Due after ten years	1,619,892
Total available-for-sale investment securities	3,335,795	$ 3,773,226
Amortized Cost
Due after ten years	143,971
Estimated Fair Value
Due after ten years	144,593
Fair value of available-for-sale investment securities pledged	$ 767,400	$ 873,000