Securities (Details 3) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale securities, Amortized Cost
Total	$ 1,414,557	$ 1,389,255
Available-for-sale securities, Fair value
Total	1,430,765	1,384,750
Total debt securities [Member]
Available-for-sale securities, Amortized Cost
Due in one year or less	33,020	53,936
Due after one year through five years	338,449	351,462
Due after five years through ten years	227,723	219,161
Due after ten years	12,229	13,098
Total	611,421	637,657
Available-for-sale securities, Fair value
Due in one year or less	33,573	54,735
Due after one year through five years	345,970	353,736
Due after five years through ten years	233,085	218,561
Due after ten years	11,948	12,749
Total	624,576	639,781
Mortgage-backed securities [Member]
Available-for-sale securities, Amortized Cost
Total	803,136	751,598
Available-for-sale securities, Fair value
Total	$ 806,189	$ 744,969