Derivatives and Hedging Activities - Fair value of derivative financial instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Derivative Asset [Abstract]
Total gross derivative instruments	$ 103,388	$ 35,007
Less: Amounts subject to master netting agreements	(295)	(401)
Less: Cash collateral received/pledged	(2,466)	0
Net amount	100,627	34,606
Derivative Liability [Abstract]
Total gross derivative instruments	33,519	15,516
Less: Amounts subject to master netting agreements	(295)	(401)
Less: Cash collateral received/pledged	(31,676)	(14,933)
Net amount	1,548	182
Derivative assets
Derivative Asset [Abstract]
Total gross derivative instruments	103,388	35,007
Derivative liabilities
Derivative Liability [Abstract]
Total gross derivative instruments	33,519	15,516
Designated as hedging instrument \| Derivative assets
Derivative Asset [Abstract]
Derivatives designated as hedging instruments	2,735	0
Designated as hedging instrument \| Derivative assets \| Brokered time deposits
Derivative Asset [Abstract]
Fair value hedge	0	0
Designated as hedging instrument \| Derivative assets \| Cash flow hedge of subordinated debt
Derivative Asset [Abstract]
Cash flow hedge	2,735	0
Designated as hedging instrument \| Derivative liabilities
Derivative Liability [Abstract]
Derivatives designated as hedging instruments	0	880
Designated as hedging instrument \| Derivative liabilities \| Brokered time deposits
Derivative Liability [Abstract]
Fair value hedge	0	880
Designated as hedging instrument \| Derivative liabilities \| Cash flow hedge of subordinated debt
Derivative Liability [Abstract]
Cash flow hedge	0	0
Not designated as hedging instrument \| Derivative assets
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	100,653	35,007
Not designated as hedging instrument \| Derivative assets \| Customer derivative positions
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	87,978	27,277
Not designated as hedging instrument \| Derivative assets \| Dealer offsets to customer derivative positions
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	1	394
Not designated as hedging instrument \| Derivative assets \| Risk participations
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	13	0
Not designated as hedging instrument \| Derivative assets \| Mortgage banking - loan commitment
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	12,381	1,970
Not designated as hedging instrument \| Derivative assets \| Mortgage banking - forward sales commitment
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	280	98
Not designated as hedging instrument \| Derivative assets \| Bifurcated embedded derivatives
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	0	5,268
Not designated as hedging instrument \| Derivative assets \| Dealer offsets to bifurcated embedded derivatives
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	0	0
Not designated as hedging instrument \| Derivative liabilities
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	33,519	14,636
Not designated as hedging instrument \| Derivative liabilities \| Customer derivative positions
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	1	446
Not designated as hedging instrument \| Derivative liabilities \| Dealer offsets to customer derivative positions
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	30,260	6,425
Not designated as hedging instrument \| Derivative liabilities \| Risk participations
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	15	12
Not designated as hedging instrument \| Derivative liabilities \| Mortgage banking - loan commitment
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	0	0
Not designated as hedging instrument \| Derivative liabilities \| Mortgage banking - forward sales commitment
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	776	86
Not designated as hedging instrument \| Derivative liabilities \| Bifurcated embedded derivatives
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	1,938	0
Not designated as hedging instrument \| Derivative liabilities \| Dealer offsets to bifurcated embedded derivatives
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	$ 529	$ 7,667

Fair value of securities received as collateral against derivative assets.

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