AVAILABLE-FOR-SALE INVESTMENT SECURITIES (Details 5) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Amortized Cost
Due within one year	$ 756,656
Due after one year through five years	1,155,873
Due after five years through ten years	554,458
Due after ten years	1,316,842
Total available-for-sale investment securities	3,783,829
Estimated Fair Value
Due within one year	752,736
Due after one year through five years	1,152,752
Due after five years through ten years	550,980
Due after ten years	1,316,758
Total available-for-sale investment securities	3,773,226	$ 2,626,617
Par value of securities pledged to secure public deposits	$ 873,000	$ 1,960,000