Investment Securities (Details 2) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investment Securities, Available-for-Sale, Amortized Cost
Due in one year or less	$ 13,199
Due after one year through five years	257,229
Due after five years through ten years	760,797
Due after ten years	2,182,430
Total	3,213,655	$ 3,512,385
Investment Securities, Available-for-Sale, Estimated Fair Value
Due in one year or less	13,210
Due after one year through five years	260,224
Due after five years through ten years	764,024
Due after ten years	2,186,372
Securities available‑for‑sale	$ 3,223,830	$ 3,559,437