Investment Securities (Details 2) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less	$ 17,879
Due after one year through five years	326,552
Due after five years through ten years	962,429
Due after ten years	2,168,647
Total securities available-for-sale	3,475,507	$ 3,213,655
Fair Value
Due in one year or less	18,352
Due after one year through five years	331,164
Due after five years through ten years	969,431
Due after ten years	2,213,283
Total securities available-for-sale	$ 3,532,230	$ 3,223,830