Investment Securities Investment Category and Length of Time (Details) $ in Thousands	Jun. 30, 2015 USD ($) investment_security	Dec. 31, 2014 USD ($) investment_security	Jun. 30, 2014 USD ($) investment_security
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number | investment_security	141	42	38
Less than 12 months, Fair Value	$ 143,721	$ 42,482	$ 51,327
Less than 12 months, Gross Unrealized Holding Losses	$ (1,184)	$ (222)	$ (252)
12 months or more, Number | investment_security	10	20	56
12 months or more, Fair Value	$ 17,950	$ 25,352	$ 70,551
12 months or more, Gross Unrealized Holding Losses	$ (634)	$ (565)	$ (1,227)
Total, Number | investment_security	151	62	94
Total, Fair Value	$ 161,671	$ 67,834	$ 121,878
Total, Gross Unrealized Holding Losses	$ (1,818)	$ (787)	$ (1,479)
Municipal bonds
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number | investment_security	109	35	27
Less than 12 months, Fair Value	$ 56,215	$ 18,129	$ 14,011
Less than 12 months, Gross Unrealized Holding Losses	$ (636)	$ (117)	$ (143)
12 months or more, Number | investment_security	7	16	44
12 months or more, Fair Value	$ 3,728	$ 6,510	$ 18,316
12 months or more, Gross Unrealized Holding Losses	$ (109)	$ (56)	$ (211)
Total, Number | investment_security	116	51	71
Total, Fair Value	$ 59,943	$ 24,639	$ 32,327
Total, Gross Unrealized Holding Losses	$ (745)	$ (173)	$ (354)
Mortgage-backed securities
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number | investment_security	32	7	11
Less than 12 months, Fair Value	$ 87,506	$ 24,353	$ 37,316
Less than 12 months, Gross Unrealized Holding Losses	$ (548)	$ (105)	$ (109)
12 months or more, Number | investment_security	3	4	12
12 months or more, Fair Value	$ 14,222	$ 18,842	$ 52,235
12 months or more, Gross Unrealized Holding Losses	$ (525)	$ (509)	$ (1,016)
Total, Number | investment_security	35	11	23
Total, Fair Value	$ 101,728	$ 43,195	$ 89,551
Total, Gross Unrealized Holding Losses	$ (1,073)	$ (614)	$ (1,125)