Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	$ 328,194	$ 320,556
Available for sale Securities, Gross Unrealized Gains	12,662	14,020
Available for sale Securities, Unrealized Losses Other	(2,792)	(2,638)
Available for sale Securities, Other Than Temporary Impairment	(2,371)	(2,652)
Available for sale Securities, Fair Value, Total	335,693	329,286
Held to maturity Securities, Amortized Cost	209,090	178,318
Held to maturity Securities, Gross Unrealized Gains	6,670	7,508
Held to maturity Securities, Unrealized Losses Other	(350)	(2)
Held to maturity Securities, Other Than Temporary Impairment
Held to Maturity, Fair Value, Total	215,410	185,824
Amortized Cost	537,284	498,874
Gross Unrealized Gains	19,332	21,528
Unrealized Losses Other	(3,142)	(2,640)
Other Than Temporary Impairment	(2,371)	(2,652)
Fair Value	551,103	515,110
U. S. Government Agency Securities [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	20,051	20,053
Available for sale Securities, Gross Unrealized Gains	685	769
Available for sale Securities, Unrealized Losses Other
Available for sale Securities, Other Than Temporary Impairment
Available for sale Securities, Fair Value, Total	20,736	20,822
U.S. Treasury Securities [Member]
Reconciliation of fair value of securities
Held to maturity Securities, Amortized Cost	1,013	1,013
Held to maturity Securities, Gross Unrealized Gains	113	121
Held to maturity Securities, Unrealized Losses Other
Held to maturity Securities, Other Than Temporary Impairment
Held to Maturity, Fair Value, Total	1,126	1,134
Agency Mortgage-Backed Securities [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	212,191	209,381
Available for sale Securities, Gross Unrealized Gains	10,642	12,158
Available for sale Securities, Unrealized Losses Other	(256)	(114)
Available for sale Securities, Other Than Temporary Impairment
Available for sale Securities, Fair Value, Total	222,577	221,425
Held to maturity Securities, Amortized Cost	63,897	72,360
Held to maturity Securities, Gross Unrealized Gains	3,698	4,233
Held to maturity Securities, Unrealized Losses Other
Held to maturity Securities, Other Than Temporary Impairment
Held to Maturity, Fair Value, Total	67,595	76,593
Agency Collateralized Mortgage Obligations [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	71,631	67,412
Available for sale Securities, Gross Unrealized Gains	899	1,001
Available for sale Securities, Unrealized Losses Other	(223)	(37)
Available for sale Securities, Other Than Temporary Impairment
Available for sale Securities, Fair Value, Total	72,307	68,376
Held to maturity Securities, Amortized Cost	136,745	97,507
Held to maturity Securities, Gross Unrealized Gains	2,512	2,875
Held to maturity Securities, Unrealized Losses Other	(350)	(2)
Held to maturity Securities, Other Than Temporary Impairment
Held to Maturity, Fair Value, Total	138,907	100,380
State, County, and Municipal Securities [Member]
Reconciliation of fair value of securities
Held to maturity Securities, Amortized Cost	916	915
Held to maturity Securities, Gross Unrealized Gains	14	11
Held to maturity Securities, Unrealized Losses Other
Held to maturity Securities, Other Than Temporary Impairment
Held to Maturity, Fair Value, Total	930	926
Private Mortgage-Backed Securities [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	3,101	3,227
Available for sale Securities, Gross Unrealized Gains
Available for sale Securities, Unrealized Losses Other
Available for sale Securities, Other Than Temporary Impairment	269	305
Available for sale Securities, Fair Value, Total	3,370	3,532
Single Issuer Trust Preferred Securities Issued by Banks and Insurers [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	2,244	2,255
Available for sale Securities, Gross Unrealized Gains	29
Available for sale Securities, Unrealized Losses Other		(15)
Available for sale Securities, Other Than Temporary Impairment
Available for sale Securities, Fair Value, Total	2,273	2,240
Held to maturity Securities, Amortized Cost	1,513	1,516
Held to maturity Securities, Gross Unrealized Gains	17	10
Held to maturity Securities, Unrealized Losses Other
Held to maturity Securities, Other Than Temporary Impairment
Held to Maturity, Fair Value, Total	1,530	1,526
Pooled Trust Preferred Securities Issued by Banks and Insurers [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	8,185	8,353
Available for sale Securities, Gross Unrealized Gains
Available for sale Securities, Unrealized Losses Other	(2,253)	(2,415)
Available for sale Securities, Other Than Temporary Impairment	(2,640)	(2,957)
Available for sale Securities, Fair Value, Total	3,292	2,981
Marketable Equity Securities [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	10,791	9,875
Available for sale Securities, Gross Unrealized Gains	407	92
Available for sale Securities, Unrealized Losses Other	(60)	(57)
Available for sale Securities, Other Than Temporary Impairment
Available for sale Securities, Fair Value, Total	11,138	9,910
Corporate Debt Securities [Member]
Reconciliation of fair value of securities
Held to maturity Securities, Amortized Cost	5,006	5,007
Held to maturity Securities, Gross Unrealized Gains	316	258
Held to maturity Securities, Unrealized Losses Other
Held to maturity Securities, Other Than Temporary Impairment
Held to Maturity, Fair Value, Total	$ 5,322	$ 5,265

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