Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk - Fair Value of Derivatives (Details)	Sep. 30, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount to be reclassified as a reduction to interest expense during the next twelve months	$ 18,000
Derivative assets designated as hedging instruments, fair value	1,135,000
Derivative liabilities designated as hedging instruments, fair value		$ 1,287,000
Derivative assets not designated as hedging instruments, fair value	2,954,000	965,000
Total Derivative liabilities not designated as hedging instruments, fair value	2,806,000	740,000
Interest Rate Products
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative assets designated as hedging instruments, classified in other assets	$ 1,135,000
Derivated liabilities designated as hedging instruments, classified in other liabilities		1,287,000
Interest Rate Products \| Designated
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative, number of transactions \| item	1
Notional Amount	$ 25,774,000
Interest Rate Products \| Commercial Loan Customers
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Interest rate derivatives, derivative assets not designated as hedging instruments, classified in other assets	2,803,000	727,000
Interest rate derivatives, derivative not designated as hedging instruments, classified in other liabilities		727,000
Other derivatives, derivative not designated as hedging instruments, classified in other liabilities	2,803,000
Interest Rate Products \| Commercial Loan Customers \| Not designated
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional Amount	168,394,000
Other Contracts
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Other derivatives, derivative not designated as hedging instruments, classified in other liabilities	$ 3,000	13,000
Other Contracts \| Not designated
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Derivative, number of transactions \| item	3
Notional Amount	$ 15,806,000
Interest Rate Lock Commitments and Forward Contracts
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Interest rate derivatives, derivative assets not designated as hedging instruments, classified in other assets	151,000	$ 238,000
Interest Rate Lock Commitments and Forward Contracts \| Not designated
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Notional Amount	$ 25,250,000

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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Fair value of all asset derivatives designated as cash flow hedging instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
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Fair value of all liability derivatives designated as cash flow hedging instruments.

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Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

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Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability.

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Fair value as of the balance sheet date of all interest rate derivative assets designated as cash flow hedging instruments.

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The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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Fair value as of the balance sheet date of all derivative assets not designated as hedging instruments.

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Fair value as of the balance sheet date of all derivative liabilities not designated as hedging instruments.

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Fair value of all derivative liabilities not designated as a hedging instrument.

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