Securities, Amortized Cost and Fair Value of Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale Debt Securities [Abstract]
Amortized cost	$ 583,939	$ 568,381
Gross unrealized gains	3,158	5,582
Gross unrealized losses	(6,061)	(3,778)
Fair value	581,036	570,185
Securities Available-for-Sale [Abstract]
Amortized cost	608,939	593,381
Gross unrealized gains	3,234	5,714
Gross unrealized losses	(6,779)	(4,159)
Available-for-sale securities	605,394	594,936
Securities Held-to-Maturity [Abstract]
Amortized cost	866	1,661
Gross unrealized gains	1	2
Gross unrealized losses	0	(12)
Fair value	867	1,651
U.S. Treasury and Government Agencies [Member]
Available-for-sale Debt Securities [Abstract]
Amortized cost	223,014	240,434
Gross unrealized gains	193	311
Gross unrealized losses	(743)	(1,351)
Fair value	222,464	239,394
State and Political Subdivisions [Member]
Available-for-sale Debt Securities [Abstract]
Amortized cost	133,351	125,665
Gross unrealized gains	1,957	3,707
Gross unrealized losses	(1,792)	(157)
Fair value	133,516	129,215
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Available-for-sale Debt Securities [Abstract]
Amortized cost	227,574	202,282
Gross unrealized gains	1,008	1,564
Gross unrealized losses	(3,526)	(2,270)
Fair value	225,056	201,576
CRA Investments Funds [Member]
Available-for-sale Equity Securities [Abstract]
Amortized cost	25,000	25,000
Gross unrealized gains	76	132
Gross unrealized losses	(718)	(381)
Fair value	24,358	24,751
U.S. Treasury and Government Agencies [Member]
Securities Held-to-Maturity [Abstract]
Amortized cost	0	480
Gross unrealized gains	0	0
Gross unrealized losses	0	(12)
Fair value	0	468
State and Political Subdivisions [Member]
Securities Held-to-Maturity [Abstract]
Amortized cost	866	1,181
Gross unrealized gains	1	2
Gross unrealized losses	0	0
Fair value	$ 867	$ 1,183