Investment Securities Investment Category and Length of Time (Details) $ in Thousands	Sep. 30, 2015 USD ($) investment_security	Dec. 31, 2014 USD ($) investment_security	Sep. 30, 2014 USD ($) investment_security
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number | investment_security	81	42	51
Less than 12 months, Fair Value	$ 95,208	$ 42,482	$ 102,052
Less than 12 months, Gross Unrealized Holding Losses	$ (387)	$ (222)	$ (439)
12 months or more, Number | investment_security	10	20	35
12 months or more, Fair Value	$ 17,225	$ 25,352	$ 52,975
12 months or more, Gross Unrealized Holding Losses	$ (425)	$ (565)	$ (1,093)
Total, Number | investment_security	91	62	86
Total, Fair Value	$ 112,433	$ 67,834	$ 155,027
Total, Gross Unrealized Holding Losses	$ (812)	$ (787)	$ (1,532)
Municipal bonds
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number | investment_security	64	35	29
Less than 12 months, Fair Value	$ 37,405	$ 18,129	$ 16,804
Less than 12 months, Gross Unrealized Holding Losses	$ (248)	$ (117)	$ (183)
12 months or more, Number | investment_security	7	16	26
12 months or more, Fair Value	$ 3,612	$ 6,510	$ 10,459
12 months or more, Gross Unrealized Holding Losses	$ (78)	$ (56)	$ (85)
Total, Number | investment_security	71	51	55
Total, Fair Value	$ 41,017	$ 24,639	$ 27,263
Total, Gross Unrealized Holding Losses	$ (326)	$ (173)	$ (268)
Mortgage-backed securities
Investment Securities Available-for-Sale, Total temporary impaired securities
Less than 12 months, Number | investment_security	17	7	22
Less than 12 months, Fair Value	$ 57,803	$ 24,353	$ 85,248
Less than 12 months, Gross Unrealized Holding Losses	$ (139)	$ (105)	$ (256)
12 months or more, Number | investment_security	3	4	9
12 months or more, Fair Value	$ 13,613	$ 18,842	$ 42,516
12 months or more, Gross Unrealized Holding Losses	$ (347)	$ (509)	$ (1,008)
Total, Number | investment_security	20	11	31
Total, Fair Value	$ 71,416	$ 43,195	$ 127,764
Total, Gross Unrealized Holding Losses	$ (486)	$ (614)	$ (1,264)