Securities, Amortized Cost and Fair Value of Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Available-for-sale debt securities [Abstract]
Amortized cost	$ 544,500	$ 568,381
Gross unrealized gains	9,894	5,582
Gross unrealized losses	(538)	(3,778)
Fair value	553,856	570,185
Available-for-sale [Abstract]
Amortized cost	569,500	593,381
Gross unrealized gains	10,252	5,714
Gross unrealized losses	(637)	(4,159)
Fair value	579,115	594,936
Held-to-maturity [Abstract]
Amortized cost	1,661	1,661
Gross unrealized gains	1	2
Gross unrealized losses	0	(12)
Fair value	1,662	1,651
U.S. Treasury and Government Agencies [Member]
Available-for-sale debt securities [Abstract]
Amortized cost	219,193	240,434
Gross unrealized gains	1,694	311
Gross unrealized losses	(26)	(1,351)
Fair value	220,861	239,394
State and Political Subdivisions [Member]
Available-for-sale debt securities [Abstract]
Amortized cost	117,611	125,665
Gross unrealized gains	5,377	3,707
Gross unrealized losses	(41)	(157)
Fair value	122,947	129,215
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Available-for-sale debt securities [Abstract]
Amortized cost	207,696	202,282
Gross unrealized gains	2,823	1,564
Gross unrealized losses	(471)	(2,270)
Fair value	210,048	201,576
CRA Investments Funds [Member]
Available-for-sale equity securities [Abstract]
Amortized cost	25,000	25,000
Gross unrealized gains	358	132
Gross unrealized losses	(99)	(381)
Fair value	25,259	24,751
U.S. Treasury and Government Agencies [Member]
Held-to-maturity [Abstract]
Amortized cost	480	480
Gross unrealized gains	0	0
Gross unrealized losses	0	(12)
Fair value	480	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