Fair Value Disclosures, Changes in Fair Value for Financial Assets (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Changes in fair value for financial assets [Abstract]
Equity Securities at fair value, net gains (losses)	$ (154)
Trading securities, net gains (losses)		$ (79)
Loans held for sale, net gains (losses)	(153)	581
Capitalized mortgage loan serviceing rights, net gains (losses)	1,029	(264)
Impairment charges recognized [Abstract]
Collateral dependent loans, carrying amount	2,000		$ 2,600
Collateral dependent loans, valuation allowance	500		700
Additional provision for loan losses on impaired loans	100	300
Other real estate, carrying amount	200		300
Other real estate, valuation allowance	100		$ 100
Other real estate, additional charge	20	20
Securities [Member]
Changes in fair value for financial assets [Abstract]
Equity Securities at fair value, net gains (losses)	(154)
Trading securities, net gains (losses)		(79)
Mortgage Loans [Member]
Changes in fair value for financial assets [Abstract]
Loans held for sale, net gains (losses)	(153)	581
Mortgage Loan Servicing [Member]
Changes in fair value for financial assets [Abstract]
Capitalized mortgage loan serviceing rights, net gains (losses)	$ 1,029	$ (264)

Loans which are measured for impairment using the fair value of collaterals.

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The valuation allowance on loans measured for impairment, using the fair value of collaterals.

+ References

No definition available.

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Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

No definition available.

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Amount of unrealized gain (loss) on loans held for sale measured at fair value with change in fair value recognized in net income.

+ References

No definition available.

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- Definition

Carrying amount of other real estate that are impaired, net reserves.

+ References

No definition available.

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- Definition

Amount of unrealized gain (loss) on capitalized servicing rights measured at fair value with change in fair value recognized in net income.

+ References

No definition available.

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Amount of unrealized gain (loss) on investment in trading security measured at fair value with change in fair value recognized in net income.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

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- Definition

Amount of expense related to write-down of receivables to the amount expected to be collected. Includes, but is not limited to, accounts receivable and notes receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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For each period for which an income statement is required, disclosure of the changes in the allowance, including balances at end of period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
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