Securities Available-for-Sale - Amortized Cost and Fair Value of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 704,624	$ 686,205
Fair Value	713,198	693,487
Obligations of the U.S. Treasury, U.S. government corporations and agencies, and obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	57,066
Due after one year through five years, Amortized Cost	196,739
Due after five years through ten years, Amortized Cost	54,282
Due after ten years, Amortized Cost	65,176
Available-for-sale Securities, Debt Maturities, Amortized Cost	373,263
Due in one year or less, Fair Value	57,302
Due after one year through five years, Fair Value	198,760
Due after five years through ten years, Fair Value	54,913
Due after ten years, Fair Value	67,867
Fair Value, Debt securities	378,842
Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	125,466	130,046
Fair Value	125,155	129,777
Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	35,132	36,606
Fair Value	35,824	37,358
Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	163,396	127,311
Fair Value	161,977	125,604
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	697,257	678,626
Fair Value	701,798	682,238
Marketable Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,367	7,579
Fair Value	$ 11,400	$ 11,249