Investment Securities - Investments in continuous loss position (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 U.S. government agencies	Dec. 31, 2012 U.S. government agencies	Mar. 31, 2013 Government sponsored agencies - Residential mortgage-backed securities	Dec. 31, 2012 Government sponsored agencies - Residential mortgage-backed securities	Mar. 31, 2013 Government sponsored agencies - Collateralized mortgage obligations SecuritiesPositions	Dec. 31, 2012 Government sponsored agencies - Collateralized mortgage obligations SecuritiesPositions	Mar. 31, 2013 Private label collateralized mortgage obligations SecuritiesPositions	Dec. 31, 2012 Private label collateralized mortgage obligations SecuritiesPositions	Mar. 31, 2013 State and municipal securities	Dec. 31, 2012 State and municipal securities	Dec. 31, 2012 Common and preferred stocks SecuritiesPositions	Dec. 31, 2011 Common and preferred stocks
Schedule of Available-for-sale Securities
Continuous unrealized loss investments, number of positions							1	3	1	1			2
Less Than 12 Months, Fair value	$ 119,905	$ 64,766	$ 2,139	$ 2,429	$ 45,645	$ 12,021	$ 15,034	$ 27,417	$ 4,752	$ 0	$ 52,335	$ 22,899		$ 0
Less Than 12 Months, Unrealized losses	1,734	826	5	1	400	325	73	127	75	0	1,181	373	0
12 Months or More, Fair value	1,854	7,864	0	0	0	0	1,682	7,626	172	178	0	0	60
12 Months or More, Unrealized losses	13	169	0	0	0	0	12	168	1	0	0	0	1
Total, Fair value	121,759	72,630	2,139	2,429	45,645	12,021	16,716	35,043	4,924	178	52,335	22,899	60
Total, Unrealized losses	$ 1,747	$ 995	$ 5	$ 1	$ 400	$ 325	$ 85	$ 295	$ 76	$ 0	$ 1,181	$ 373	$ 1