Investment Securities (Details 3) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Due in one year or less	$ 12,821
Due after one year through five years	216,420
Due after five years through ten years	603,523
Due after ten years	2,325,787
Total securities available-for-sale	3,158,551	$ 3,512,385
Fair Value Disclosures [Abstract]
Due in one year or less	12,628
Due after one year through five years	219,110
Due after five years through ten years	619,214
Due after ten years	2,389,634
Total securities available-for-sale	$ 3,240,586	$ 3,559,437