Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Details) - Not Designated as Hedging Instruments - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Other Assets
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	$ 10,645,000	$ 5,504,000
Other Assets \| Interest rate swap contracts—commercial loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	10,645,000	5,504,000
Notional amount, Derivatives (included in Other Assets)	367,258,000	325,750,000
Collateral received/posted, Derivatives (included in Other Assets)	0	160,000
Other Assets \| Interest rate lock commitments—mortgage loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	339,000	251,000
Notional amount, Derivatives (included in Other Assets)	10,554,000	6,054,000
Other Assets \| Forward sale contracts—mortgage loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	88,000	55,000
Notional amount, Derivatives (included in Other Assets)	9,375,000	6,000,000
Other Liabilities
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	10,602,000	5,340,000
Other Liabilities \| Interest rate swap contracts—commercial loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	10,602,000	5,340,000
Notional amount, Derivatives (included in Other Liabilities)	367,258,000	325,750,000
Collateral received/posted, Derivatives (included in Other Liabilities)	10,053,000	0
Other Liabilities \| Interest rate lock commitments—mortgage loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	0	0
Notional amount, Derivatives (included in Other Liabilities)	0	0
Other Liabilities \| Forward sale contracts—mortgage loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	0	0
Notional amount, Derivatives (included in Other Liabilities)	$ 0	$ 0

Fair value of securities received as collateral against derivative assets.

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-Topic 210
-SubTopic 20
-Section 55
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Nominal or face amount used to calculate payments on the derivative asset.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Fair value of securities pledged as collateral against derivative liabilities.

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Nominal or face amount used to calculate payments on the derivative liability.

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