Investment Securities (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013 item	Dec. 31, 2012 item	Jun. 30, 2012 item
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	151	3	19
Less than 12 months, Fair Value	$ 138,877	$ 15,420	$ 26,335
Less than 12 months, Gross Unrealized Holding Losses	(3,652)	(153)	(153)
12 months or more, Number	17	31	41
12 months or more, Fair Value	713	1,012	1,185
12 months or more, Gross Unrealized Holding Losses	(138)	(330)	(540)
Total, Number	168	34	60
Total, Fair Value	139,590	16,432	27,520
Total, Gross Unrealized Holding Losses	(3,790)	(483)	(693)
Municipal bonds
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	122	1	12
Less than 12 months, Fair Value	51,937	292	5,245
Less than 12 months, Gross Unrealized Holding Losses	(1,736)	(1)	(71)
Total, Number	122	1	12
Total, Fair Value	51,937	292	5,245
Total, Gross Unrealized Holding Losses	(1,736)	(1)	(71)
Mortgage-backed securities
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	29	2	7
Less than 12 months, Fair Value	86,940	15,128	21,090
Less than 12 months, Gross Unrealized Holding Losses	(1,916)	(152)	(82)
12 months or more, Number	17	31	41
12 months or more, Fair Value	713	1,012	1,185
12 months or more, Gross Unrealized Holding Losses	(138)	(330)	(540)
Total, Number	46	33	48
Total, Fair Value	87,653	16,140	22,275
Total, Gross Unrealized Holding Losses	$ (2,054)	$ (482)	$ (622)