Investment Securities Amortized Cost and Estimated Fair Value of Held to Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 249,250	$ 275,919	$ 198,135
Unrealized Gains	3,671	5,998	4,315
Unrealized Losses	(4,223)	(2,213)	(6,900)
Fair Value (Estimated)	248,698	279,704	195,550
U.S. Government-sponsored agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	75,982	92,341	92,324
Unrealized Gains	45	54	5
Unrealized Losses	(3,035)	(2,066)	(6,343)
Fair Value (Estimated)	72,992	90,329	85,986
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	48,655	57,003	65,835
Unrealized Gains	1,650	1,830	1,851
Unrealized Losses	(125)	(116)	(526)
Fair Value (Estimated)	50,180	58,717	67,160
State and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	124,313	126,275	39,676
Unrealized Gains	1,976	4,114	2,459
Unrealized Losses	(1,063)	(31)	(31)
Fair Value (Estimated)	125,226	130,358	42,104
Corporate securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	300	300	300
Unrealized Gains	0	0	0
Unrealized Losses	0	0	0
Fair Value (Estimated)	$ 300	$ 300	$ 300

Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity.

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Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-Section 50

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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