Securities - Amortized Cost and Estimated Fair Value of Securities - Securities Held-to-maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Securities held-to-maturity:
Amortized Cost	$ 366,560	$ 377,198
Gross Unrealized Gains	2,519	371
Gross Unrealized (Losses)	(972)	(11,394)
Estimated Fair Value	368,107	366,175
Agency mortgage-backed securities
Securities held-to-maturity:
Amortized Cost	285,344	291,241
Gross Unrealized Gains	1,206	59
Gross Unrealized (Losses)	(968)	(9,153)
Estimated Fair Value	285,582	282,147
Municipals - exempt from Federal tax
Securities held-to-maturity:
Amortized Cost	81,216	85,957
Gross Unrealized Gains	1,313	312
Gross Unrealized (Losses)	(4)	(2,241)
Estimated Fair Value	$ 82,525	$ 84,028

Not applicable.

No definition available.

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- Definition

Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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- Definition

Amount, before other-than-temporary impairment (OTTI) accretion, of investment in debt securities measured at amortized cost (held-to-maturity).

+ References

No definition available.

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- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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