Investment Securities (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013 item	Dec. 31, 2012 item	Sep. 30, 2012 item
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	170	3	13
Less than 12 months, Fair Value	$ 196,696	$ 15,420	$ 11,800
Less than 12 months, Gross Unrealized Holding Losses	(4,520)	(153)	(48)
12 months or more, Number	1	31	34
12 months or more, Fair Value	13,117	1,012	1,004
12 months or more, Gross Unrealized Holding Losses	(860)	(330)	(446)
Total, Number	171	34	47
Total, Fair Value	209,813	16,432	12,804
Total, Gross Unrealized Holding Losses	(5,380)	(483)	(494)
Municipal bonds
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	131	1	9
Less than 12 months, Fair Value	60,183	292	2,775
Less than 12 months, Gross Unrealized Holding Losses	(1,795)	(1)	(15)
Total, Number	131	1	9
Total, Fair Value	60,183	292	2,775
Total, Gross Unrealized Holding Losses	(1,795)	(1)	(15)
Mortgage-backed securities
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number	39	2	4
Less than 12 months, Fair Value	136,513	15,128	9,025
Less than 12 months, Gross Unrealized Holding Losses	(2,725)	(152)	(33)
12 months or more, Number	1	31	34
12 months or more, Fair Value	13,117	1,012	1,004
12 months or more, Gross Unrealized Holding Losses	(860)	(330)	(446)
Total, Number	40	33	38
Total, Fair Value	149,630	16,140	10,029
Total, Gross Unrealized Holding Losses	$ (3,585)	$ (482)	$ (479)