Investment Securities (Details 3) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Due in one year or less	$ 14,761
Due after one year through five years	230,982
Due after five years through ten years	713,952
Due after ten years	2,249,690
Total securities available-for-sale	3,209,385	$ 3,512,385
Fair Value Disclosures [Abstract]
Due in one year or less	14,834
Due after one year through five years	235,996
Due after five years through ten years	736,838
Due after ten years	2,359,878
Total securities available-for-sale	$ 3,347,546	$ 3,559,437