Investment Securities (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 item	Dec. 31, 2012 item	Mar. 31, 2012 item
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	125	3	22
Less than 12 months, Fair Value	$ 74,031	$ 15,420	$ 33,172
Less than 12 months, Gross Unrealized Holding Losses	(737)	(153)	(366)
12 months or more, Number	27	31	39
12 months or more, Fair Value	1,031	1,012	1,368
12 months or more, Gross Unrealized Holding Losses	(217)	(330)	(714)
Total, Number	152	34	61
Total, Fair Value	75,062	16,432	34,540
Total, Gross Unrealized Holding Losses	(954)	(483)	(1,080)
Corporate bonds
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number			1
Less than 12 months, Fair Value			4,817
Less than 12 months, Gross Unrealized Holding Losses			(183)
Total, Number			1
Total, Fair Value			4,817
Total, Gross Unrealized Holding Losses			(183)
Municipal bonds
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	122	1	8
Less than 12 months, Fair Value	53,773	292	2,832
Less than 12 months, Gross Unrealized Holding Losses	(387)	(1)	(96)
Total, Number	122	1	8
Total, Fair Value	53,773	292	2,832
Total, Gross Unrealized Holding Losses	(387)	(1)	(96)
Mortgage-backed securities
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	3	2	13
Less than 12 months, Fair Value	20,258	15,128	25,523
Less than 12 months, Gross Unrealized Holding Losses	(350)	(152)	(87)
12 months or more, Number	27	31	39
12 months or more, Fair Value	1,031	1,012	1,368
12 months or more, Gross Unrealized Holding Losses	(217)	(330)	(714)
Total, Number	30	33	52
Total, Fair Value	21,289	16,140	26,891
Total, Gross Unrealized Holding Losses	$ (567)	$ (482)	$ (801)