Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Assets:
Securities available-for-sale	$ 541,248	$ 541,439
Mortgage servicing rights	7,357	6,944
U.S. Treasury
Assets:
Securities available-for-sale	3,923	3,947
U.S. government agencies
Assets:
Securities available-for-sale		13,061
States and political subdivisions
Assets and liabilities measured at fair value on a recurring basis
Purchases	22,046	16,712
Assets:
Securities available-for-sale	274,067	278,092
Corporate bonds
Assets:
Securities available-for-sale		833
Collateralized mortgage obligations
Assets:
Securities available-for-sale	64,429	65,939
Asset-backed securities
Assets:
Securities available-for-sale	109,514	112,932
Collateralized loan obligations
Assets:
Securities available-for-sale	64,289	54,421
Level 1
Assets:
Securities available-for-sale	3,923	3,947
Level 2
Assets:
Securities available-for-sale	529,160	520,963
Loans held-for-sale	2,984	4,067
Level 2 \| Interest rate swap agreements net of swap credit valuation
Liabilities:
Other liabilities	58	1,287
Level 3
Assets:
Securities available-for-sale	8,165	16,529
Recurring
Assets:
Loans held-for-sale	2,984	4,067
Mortgage servicing rights	7,357	6,944
Total financial assets	552,420	553,415
Liabilities:
Total	672	2,014
Recurring \| Interest rate swap agreements net of swap credit valuation
Assets:
Other assets	672	727
Liabilities:
Other liabilities	672	2,014
Recurring \| Forward MBS contracts and forward loan contracts
Assets:
Other assets	159	238
Recurring \| U.S. Treasury
Assets:
Securities available-for-sale	3,923	3,947
Recurring \| U.S. government agencies
Assets:
Securities available-for-sale	10,951	13,061
Recurring \| U.S. government agency mortgage-backed
Assets:
Securities available-for-sale	14,075	12,214
Recurring \| States and political subdivisions
Assets:
Securities available-for-sale	274,067	278,092
Recurring \| Corporate bonds
Assets:
Securities available-for-sale		833
Recurring \| Collateralized mortgage obligations
Assets:
Securities available-for-sale	64,429	65,939
Recurring \| Asset-backed securities
Assets:
Securities available-for-sale	109,514	112,932
Recurring \| Collateralized loan obligations
Assets:
Securities available-for-sale	64,289	54,421
Recurring \| Level 1
Assets:
Total financial assets	3,923	3,947
Recurring \| Level 1 \| U.S. Treasury
Assets:
Securities available-for-sale	3,923	3,947
Recurring \| Level 2
Assets:
Loans held-for-sale	2,984	4,067
Total financial assets	532,975	525,995
Liabilities:
Total	672	2,014
Recurring \| Level 2 \| Interest rate swap agreements net of swap credit valuation
Assets:
Other assets	672	727
Liabilities:
Other liabilities	672	2,014
Recurring \| Level 2 \| Forward MBS contracts and forward loan contracts
Assets:
Other assets	159	238
Recurring \| Level 2 \| U.S. government agencies
Assets:
Securities available-for-sale	10,951	13,061
Recurring \| Level 2 \| U.S. government agency mortgage-backed
Assets:
Securities available-for-sale	14,075	12,214
Recurring \| Level 2 \| States and political subdivisions
Assets:
Securities available-for-sale	265,902	263,831
Recurring \| Level 2 \| Corporate bonds
Assets:
Securities available-for-sale		833
Recurring \| Level 2 \| Collateralized mortgage obligations
Assets:
Securities available-for-sale	64,429	63,671
Recurring \| Level 2 \| Asset-backed securities
Assets:
Securities available-for-sale	109,514	112,932
Recurring \| Level 2 \| Collateralized loan obligations
Assets:
Securities available-for-sale	64,289	54,421
Recurring \| Level 3
Assets:
Mortgage servicing rights	7,357	6,944
Total financial assets	15,522	23,473
Recurring \| Level 3 \| States and political subdivisions
Assets:
Securities available-for-sale	$ 8,165	14,261
Recurring \| Level 3 \| Collateralized mortgage obligations
Assets:
Securities available-for-sale		$ 2,268

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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