Investment Securities (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	$ 365,755	$ 291,103
Unrealized gains	8,236	5,737
Unrealized losses	(1,023)	(885)
Fair value	372,968	295,955
Available-for-sale securities continuous unrealized loss position fair value [Abstract]
Less than 12 Months, Fair value	59,705	51,879
12 Months or Longer, Fair value	12,428	2,006
Total Fair value	72,133	53,885
Less than 12 Months, Unrealized losses	(433)	(873)
12 Months or Longer, Unrealized losses	(590)	(12)
Total Unrealized losses	(1,023)	(885)
Number of securities temporarily impaired	25	10
Other-than-temporary impairment losses on investment security	0	0
Available-for-sale securities debt maturities amortized cost basis fiscal year maturity [Abstract]
Three months or less	10,032
Over three months to one year	3,452
After one year through three years	38,575
After three years through five years	228,275
After five years through ten years	60,818
After ten years	24,603
Total Amortized cost	365,755
Available-for-sale securities debt maturities fair value fiscal year maturity [Abstract]
Three months or less	10,059
Over three months to one year	3,447
After one year through three years	39,102
After three years through five years	232,530
After five years through ten years	61,977
After ten years	25,853
Total Fair value	372,968
Securities pledged to secure public deposits, borrowings and other items, Amortized cost [Abstract]
To state and local governments to secure public deposits, Amortized cost	61,600
To Federal Reserve Bank to secure borrowings, Amortized cost	17,537
To Federal Home Loan Bank to secure borrowings, Amortized cost	559
Other securities pledged, principally to secure deposits, Amortized cost	14,632
Total pledged investment securities, Amortized cost	94,328
Securities pledged to secure public deposits, borrowings and other items, Fair value [Abstract]
To state and local governments to secure public deposits, Fair value	64,045
To Federal Reserve Bank to secure borrowings, Fair value	18,130
To Federal Home Loan Bank to secure borrowings, Fair value	585
Other securities pledged, principally to secure deposits, Fair value	15,336
Total pledged investment securities, Fair value	98,096
Gross realized gains on investment securities available for sale	933
Gross realized losses on investment securities available for sale	2
U.S. government agencies [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	87,297	75,383
Unrealized gains	1,321	1,207
Unrealized losses	(32)	(16)
Fair value	88,586	76,574
Available-for-sale securities continuous unrealized loss position fair value [Abstract]
Less than 12 Months, Fair value	12,056	10,499
12 Months or Longer, Fair value	0	0
Total Fair value	12,056	10,499
Less than 12 Months, Unrealized losses	(32)	(16)
12 Months or Longer, Unrealized losses	0	0
Total Unrealized losses	(32)	(16)
U.S. Treasuries [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost		42,077
Unrealized gains		520
Unrealized losses		0
Fair value		42,597
Residential pass-through securities [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	165,175	116,219
Unrealized gains	3,430	1,295
Unrealized losses	(182)	(116)
Fair value	168,423	117,398
Available-for-sale securities continuous unrealized loss position fair value [Abstract]
Less than 12 Months, Fair value	27,680	29,838
12 Months or Longer, Fair value	0	0
Total Fair value	27,680	29,838
Less than 12 Months, Unrealized losses	(182)	(116)
12 Months or Longer, Unrealized losses	0	0
Total Unrealized losses	(182)	(116)
Taxable state and political subdivisions [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	4,759	9,143
Unrealized gains	553	615
Unrealized losses	0	0
Fair value	5,312	9,758
Tax exempt states and political subdivisions [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	56,431	35,263
Unrealized gains	2,703	2,100
Unrealized losses	(149)	(28)
Fair value	58,985	37,335
Available-for-sale securities continuous unrealized loss position fair value [Abstract]
Less than 12 Months, Fair value	10,113	1,255
12 Months or Longer, Fair value	0	0
Total Fair value	10,113	1,255
Less than 12 Months, Unrealized losses	(149)	(28)
12 Months or Longer, Unrealized losses	0	0
Total Unrealized losses	(149)	(28)
Corporate obligations [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	11,000	11,000
Unrealized gains	0	0
Unrealized losses	(565)	(713)
Fair value	10,435	10,287
Available-for-sale securities continuous unrealized loss position fair value [Abstract]
Less than 12 Months, Fair value	0	10,287
12 Months or Longer, Fair value	10,435	0
Total Fair value	10,435	10,287
Less than 12 Months, Unrealized losses	0	(713)
12 Months or Longer, Unrealized losses	(565)	0
Total Unrealized losses	(565)	(713)
Agency-issued collateralized mortgage obligations [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	13,967
Unrealized gains	79
Unrealized losses	0
Fair value	14,046
Asset-backed securities [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	25,108
Unrealized gains	150
Unrealized losses	(70)
Fair value	25,188
Available-for-sale securities continuous unrealized loss position fair value [Abstract]
Less than 12 Months, Fair value	9,856
12 Months or Longer, Fair value	0
Total Fair value	9,856
Less than 12 Months, Unrealized losses	(70)
12 Months or Longer, Unrealized losses	0
Total Unrealized losses	(70)
Investments in mutual funds and other equities [Member]
Available-for-sale securities balance sheet reported amounts [Abstract]
Amortized cost	2,018	2,018
Unrealized gains	0	0
Unrealized losses	(25)	(12)
Fair value	1,993	2,006
Available-for-sale securities continuous unrealized loss position fair value [Abstract]
Less than 12 Months, Fair value	0	0
12 Months or Longer, Fair value	1,993	2,006
Total Fair value	1,993	2,006
Less than 12 Months, Unrealized losses	0	0
12 Months or Longer, Unrealized losses	(25)	(12)
Total Unrealized losses	$ (25)	$ (12)