Investment Securities - Held-To-Maturity Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Held-to-maturity Securities
Amortized Cost	$ 657,176	$ 623,427
Unrealized Gains	5,904	2,648
Unrealized Losses	7,121	17,544
Held-to-maturity, fair value	655,959	608,531
State and political subdivisions
Held-to-maturity Securities
Amortized Cost	656,676	622,927
Unrealized Gains	5,904	2,648
Unrealized Losses	6,986	17,354
Held-to-maturity, fair value	655,594	608,221
Trust preferred securities
Held-to-maturity Securities
Amortized Cost	500	500
Unrealized Gains	0	0
Unrealized Losses	135	190
Held-to-maturity, fair value	$ 365	$ 310

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

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- Definition

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

+ References

+ Details

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- Definition

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

+ References

No definition available.

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- Definition

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=82897076&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

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