Securities, Available-for-sale Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale [Abstract]
Amortized cost	$ 601,544	$ 602,114
Gross unrealized gains	3,755	1,078
Gross unrealized losses	(6,000)	(9,446)
Fair value	599,299	593,746
U.S. Treasury and Government Agencies [Member]
Available-for-sale [Abstract]
Amortized cost	178,233	219,358
Gross unrealized gains	195	48
Gross unrealized losses	(951)	(1,468)
Fair value	177,477	217,938
State and Political Subdivisions [Member]
Available-for-sale [Abstract]
Amortized cost	123,147	126,280
Gross unrealized gains	1,524	633
Gross unrealized losses	(942)	(2,425)
Fair value	123,729	124,488
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Available-for-sale [Abstract]
Amortized cost	299,658	255,969
Gross unrealized gains	2,036	397
Gross unrealized losses	(4,103)	(5,547)
Fair value	297,591	250,819
Other Debt Securities [Member]
Available-for-sale [Abstract]
Amortized cost	506	507
Gross unrealized gains	0	0
Gross unrealized losses	(4)	(6)
Fair value	$ 502	$ 501

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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