Securities (Details) (USD $)	3 Months Ended																	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 U.S. Government Agencies [Member]	Dec. 31, 2012 U.S. Government Agencies [Member]	Mar. 31, 2013 Obligations of States and Political Subdivisions [Member]	Dec. 31, 2012 Obligations of States and Political Subdivisions [Member]	Mar. 31, 2013 Mortgage-backed Securities, Agency [Member]	Dec. 31, 2012 Mortgage-backed Securities, Agency [Member]	Mar. 31, 2013 Mortgage-backed Securities, Non-agency [Member]	Dec. 31, 2012 Mortgage-backed Securities, Non-agency [Member]	Mar. 31, 2013 Other Asset Backed Securities [Member]	Dec. 31, 2012 Other Asset Backed Securities [Member]	Mar. 31, 2013 Corporate Preferred Stock [Member]	Dec. 31, 2012 Corporate Preferred Stock [Member]	Mar. 31, 2013 Corporate Securities [Member]	Dec. 31, 2012 Corporate Securities [Member]	Sep. 30, 2012 Trust-Preferred Securities [Member]	Jun. 30, 2012 Trust-Preferred Securities [Member]	Dec. 31, 2011 Trust-Preferred Securities [Member]	Dec. 31, 2012 Trust-Preferred Securities [Member]	Mar. 31, 2013 Mortgage-backed Securities [Member]
Amortized costs and fair values of securities available for sale [Abstract]
Amortized Cost	$ 321,763,000		$ 309,196,000	$ 14,837,000	$ 15,391,000	$ 79,278,000	$ 74,485,000	$ 164,305,000	$ 161,564,000	$ 19,277,000	$ 15,310,000	$ 34,268,000	$ 33,648,000	$ 68,000	$ 68,000	$ 9,730,000	$ 8,730,000				$ 0
Gross Unrealized Gains	10,916,000		11,416,000	442,000	459,000	3,415,000	3,920,000	5,630,000	5,659,000	223,000	287,000	1,165,000	1,079,000	0	0	41,000	12,000				0
Gross Unrealized Losses	(1,029,000)		(1,155,000)	(35,000)	(28,000)	(229,000)	(105,000)	(335,000)	(280,000)	(101,000)	(18,000)	(72,000)	(85,000)	(1,000)	(6,000)	(256,000)	(633,000)				0
Fair Value	331,650,000		319,457,000	15,244,000	15,822,000	82,464,000	78,300,000	169,600,000	166,943,000	19,399,000	15,579,000	35,361,000	34,642,000	67,000	62,000	9,515,000	8,109,000				0
Amortized Cost [Abstract]
Due in one year or less	4,601,000
Due after one year through five years	33,133,000
Due after five years through ten years	28,179,000
Due after ten years	37,932,000
Total	321,763,000											34,268,000		68,000								183,582,000
Fair Value [Abstract]
Due in one year or less	4,660,000
Due after one year through five years	34,410,000
Due after five years through ten years	29,374,000
Due after ten years	38,779,000
Total	331,650,000											35,361,000		67,000								188,999,000
Proceeds from sales of securities	3,900,000
Net gains realized on sale of securities	47,000
Tax expense related to realized gains	16,000
Net impairment losses	0	0
Carrying value of securities pledged for fiduciary powers	130,400,000
Fair Value [Abstract]
Less than Twelve Months	48,180,000		41,246,000	3,742,000	3,850,000	9,687,000	6,966,000	23,803,000	24,344,000	9,205,000	3,295,000	1,743,000	2,791,000	0	0	0	0				0
Twelve Months or Greater	6,980,000		9,575,000	16,000	16,000	0	0	1,528,000	1,241,000	0	0	1,154,000	1,418,000	38,000	33,000	4,244,000	6,867,000				0
Total	55,160,000		50,821,000	3,758,000	3,866,000	9,687,000	6,966,000	25,331,000	25,585,000	9,205,000	3,295,000	2,897,000	4,209,000	38,000	33,000	4,244,000	6,867,000				0
Gross Unrealized Losses [Abstract]
Less than Twelve Months	(698,000)		(442,000)	(35,000)	(28,000)	(229,000)	(105,000)	(277,000)	(234,000)	(101,000)	(18,000)	(56,000)	(57,000)	0	0	0	0				0
Twelve Months or Greater	(331,000)		(713,000)	0	0	0	0	(58,000)	(46,000)	0	0	(16,000)	(28,000)	(1,000)	(6,000)	(256,000)	(633,000)				0
Total	(1,029,000)		(1,155,000)	(35,000)	(28,000)	(229,000)	(105,000)	(335,000)	(280,000)	(101,000)	(18,000)	(72,000)	(85,000)	(1,000)	(6,000)	(256,000)	(633,000)				0
Gain on securities available for sale																		149,000	142,000
Credit losses recognized in prior period earnings	$ 0	$ 0																$ 0		$ 2,400,000