Securities (Details) - USD ($)
$ in Thousands
Sep. 30, 2016
Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 1,352,845 $ 1,390,255
Gross Unrealized Gains 21,468 9,546
Gross Unrealized Losses 3,202 14,117
Fair Value 1,371,111 1,385,684
Obligations of U.S. Government Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 513,251 551,176
Gross Unrealized Gains 13,447 3,512
Gross Unrealized Losses 2 1,795
Fair Value 526,696 552,893
Obligations of U.S. States and Political Subdivisions [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 83,596 83,981
Gross Unrealized Gains 1,098 898
Gross Unrealized Losses 13 153
Fair Value 84,681 84,726
Residential Mortgage-Backed Securities U.S. Government Agencies [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 160,464 94,459
Gross Unrealized Gains 1,721 1,535
Gross Unrealized Losses 436 1,316
Fair Value 161,749 94,678
Residential Mortgage-Backed Securities U.S. Government Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 591,908 656,947
Gross Unrealized Gains 5,202 3,599
Gross Unrealized Losses 2,357 10,449
Fair Value 594,753 650,097
Residential Mortgage-Backed Securities Non-U.S. Government Agencies or Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 126 192
Gross Unrealized Gains 0 2
Gross Unrealized Losses 0 0
Fair Value 126 194
U.S. corporate Debt Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 2,500 2,500
Gross Unrealized Gains 0 0
Gross Unrealized Losses 338 338
Fair Value 2,162 2,162
Total debt securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 1,351,845 1,389,255
Gross Unrealized Gains 21,468 9,546
Gross Unrealized Losses 3,146 14,051
Fair Value 1,370,167 1,384,750
Equity Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 1,000 1,000
Gross Unrealized Gains 0 0
Gross Unrealized Losses 56 66
Fair Value $ 944 $ 934