Investment Securities (Details 2) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 28,716
Due after one year through five years	539,423
Due after five years through ten years	1,010,453
Due after ten years	2,364,116
Total securities available-for-sale	3,942,708	$ 4,017,909
Fair Value
Due in one year or less	28,703
Due after one year through five years	543,189
Due after five years through ten years	1,013,236
Due after ten years	2,409,580
Total securities available-for-sale	$ 3,994,708	$ 4,009,431