Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Details) - Not Designated as Hedging Instruments - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Other Assets
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	$ 32,825	$ 5,504
Other Assets \| Interest rate swap contracts—commercial loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	32,825	5,504
Notional amount, Derivatives (included in Other Assets)	547,151	325,750
Collateral received/posted, Derivatives (included in Other Assets)	0	160
Other Assets \| Interest rate lock commitments—mortgage loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	455	251
Notional amount, Derivatives (included in Other Assets)	16,788	6,054
Other Assets \| Forward sale contracts—mortgage loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	64	55
Notional amount, Derivatives (included in Other Assets)	24,750	6,000
Other Liabilities
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	32,772	5,340
Other Liabilities \| Interest rate swap contracts—commercial loans
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	32,772	5,340
Notional amount, Derivatives (included in Other Liabilities)	547,151	325,750
Collateral received/posted, Derivatives (included in Other Liabilities)	32,208	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
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Nominal or face amount used to calculate payments on the derivative asset.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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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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