Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Assets:
Securities available-for-sale	$ 533,484	$ 531,838
Mortgage servicing rights	6,684	6,489
U.S. Treasury
Assets:
Securities available-for-sale	3,990
U.S. government agencies
Assets:
Securities available-for-sale	13,451	41,534
U.S. government agency mortgage-backed
Assets:
Securities available-for-sale	11,030
States and political subdivisions
Assets and liabilities measured at fair value on a recurring basis
Purchases	10,994
Assets:
Securities available-for-sale	229,032	68,703
Corporate bonds
Assets:
Securities available-for-sale	10,577	10,630
Collateralized mortgage obligations
Assets:
Securities available-for-sale	80,386	170,927
Asset-backed securities
Assets:
Securities available-for-sale	131,759	138,407
Collateralized loan obligations
Assets:
Securities available-for-sale	53,259	101,637
Level 1
Assets:
Securities available-for-sale	3,990
Level 2
Assets:
Securities available-for-sale	514,642	506,493
Loans held-for-sale	1,641	4,918
Liabilities:
Other liabilities	1,439	994
Level 3
Assets:
Securities available-for-sale	14,852	25,345
Recurring
Assets:
Total financial assets	542,226	544,205
Liabilities:
Total	1,566	1,667
Recurring \| Finite-Lived Intangible Assets [Member]
Assets:
Loans held-for-sale	1,641	4,918
Mortgage servicing rights	6,684	6,489
Recurring \| Interest rate swap agreements net of swap credit valuation
Liabilities:
Other liabilities	1,566	1,667
Recurring \| Interest rate swap agreements net of swap credit valuation \| Finite-Lived Intangible Assets [Member]
Assets:
Other assets	128	673
Recurring \| Forward MBS contracts and forward loan contracts \| Finite-Lived Intangible Assets [Member]
Assets:
Other assets	289	287
Recurring \| U.S. Treasury \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	3,990
Recurring \| U.S. government agencies \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	13,451
Recurring \| U.S. government agency mortgage-backed \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	11,030	41,534
Recurring \| States and political subdivisions \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	229,032	68,703
Recurring \| Corporate bonds \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	10,577	10,630
Recurring \| Collateralized mortgage obligations \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	80,386	170,927
Recurring \| Asset-backed securities \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	131,759	138,407
Recurring \| Collateralized loan obligations \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	53,259	101,637
Recurring \| Level 1
Assets:
Total financial assets	3,990
Recurring \| Level 1 \| U.S. Treasury \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	3,990
Recurring \| Level 2
Assets:
Total financial assets	516,700	512,371
Liabilities:
Total	1,566	1,667
Recurring \| Level 2 \| Finite-Lived Intangible Assets [Member]
Assets:
Loans held-for-sale	1,641	4,918
Recurring \| Level 2 \| Interest rate swap agreements net of swap credit valuation
Liabilities:
Other liabilities	1,566	1,667
Recurring \| Level 2 \| Interest rate swap agreements net of swap credit valuation \| Finite-Lived Intangible Assets [Member]
Assets:
Other assets	128	673
Recurring \| Level 2 \| Forward MBS contracts and forward loan contracts \| Finite-Lived Intangible Assets [Member]
Assets:
Other assets	289	287
Recurring \| Level 2 \| U.S. government agencies \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	13,451
Recurring \| Level 2 \| U.S. government agency mortgage-backed \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	11,030	41,534
Recurring \| Level 2 \| States and political subdivisions \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	216,672	46,477
Recurring \| Level 2 \| Corporate bonds \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	10,577	10,630
Recurring \| Level 2 \| Collateralized mortgage obligations \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	77,894	167,808
Recurring \| Level 2 \| Asset-backed securities \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	131,759	138,407
Recurring \| Level 2 \| Collateralized loan obligations \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	53,259	101,637
Recurring \| Level 3
Assets:
Total financial assets	21,536	31,834
Recurring \| Level 3 \| Finite-Lived Intangible Assets [Member]
Assets:
Mortgage servicing rights	6,684	6,489
Recurring \| Level 3 \| States and political subdivisions \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	12,360	22,226
Recurring \| Level 3 \| Collateralized mortgage obligations \| Finite-Lived Intangible Assets [Member]
Assets:
Securities available-for-sale	$ 2,492	$ 3,119

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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