Fair Value Measurements - Textual (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets and other real estate owned	$ 18,952,000	$ 25,565,000
Impaired loan, related allowance	521,000	684,000
Collateral dependent
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loan, related allowance	$ 0	2,738,000
Commercial Real Estate \| Discount Rate \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input (as percent)	10.00%
Commercial Real Estate \| Discount Rate \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input (as percent)	40.00%
Residential Real Estate \| Discount Rate \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input (as percent)	10.00%
Residential Real Estate \| Discount Rate \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input (as percent)	40.00%
Foreclosed Assets Not Covered By FDIC Loss Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed assets and other real estate owned	$ 19,000,000	25,600,000
Ratings of Substandard or worse
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Threshold value for performing impairment testing on loans	1,500,000
Residential Mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of financing receivable, held-for-sale	$ 0	$ 0

For collateral dependent loans, impairment testing for all loans begins at this amount.

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- Definition

Impairment of Financing Receivable, Held-for-sale

+ References

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- Definition

Other Real Estate Owned, Collateral Discount, Percentage

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- Definition

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- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5162-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4437-111522

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