Securities, Amortized Cost and Fair Value of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Available-for-sale debt securities [Abstract]
Amortized cost	$ 599,418	$ 568,381
Gross unrealized gains	7,777	5,582
Gross unrealized losses	(1,138)	(3,778)
Fair value	606,057	570,185
Available-for-sale [Abstract]
Amortized cost	624,418	593,381
Gross unrealized gains	8,070	5,714
Gross unrealized losses	(1,287)	(4,159)
Fair value	631,201	594,936
Held-to-maturity [Abstract]
Amortized cost	1,181	1,661
Gross unrealized gains	1	2
Gross unrealized losses	0	(12)
Fair value	1,182	1,651
U.S. Treasury and Government Agencies [Member]
Available-for-sale debt securities [Abstract]
Amortized cost	243,980	240,434
Gross unrealized gains	1,311	311
Gross unrealized losses	(180)	(1,351)
Fair value	245,111	239,394
State and Political Subdivisions [Member]
Available-for-sale debt securities [Abstract]
Amortized cost	128,644	125,665
Gross unrealized gains	4,646	3,707
Gross unrealized losses	(115)	(157)
Fair value	133,175	129,215
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Available-for-sale debt securities [Abstract]
Amortized cost	226,794	202,282
Gross unrealized gains	1,820	1,564
Gross unrealized losses	(843)	(2,270)
Fair value	227,771	201,576
CRA Investments Funds [Member]
Available-for-sale equity securities [Abstract]
Amortized cost	25,000	25,000
Gross unrealized gains	293	132
Gross unrealized losses	(149)	(381)
Fair value	25,144	24,751
U.S. Treasury and Government Agencies [Member]
Held-to-maturity [Abstract]
Amortized cost		480
Gross unrealized gains		0
Gross unrealized losses		(12)
Fair value		468
State and Political Subdivisions [Member]
Held-to-maturity [Abstract]
Amortized cost	1,181	1,181
Gross unrealized gains	1	2
Gross unrealized losses	0	0
Fair value	$ 1,182	$ 1,183