Derivatives and Hedging Activities - Fair value of derivative financial instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivative Asset [Abstract]
Total gross derivative instruments	$ 82,668	$ 35,007
Less: Amounts subject to master netting agreements	(50)	(401)
Less: Cash collateral received/pledged	0	0
Net amount	82,618	34,606
Derivative Liability [Abstract]
Total gross derivative instruments	27,349	15,516
Less: Amounts subject to master netting agreements	(50)	(401)
Less: Cash collateral received/pledged	(23,718)	(14,933)
Derivatives designated as hedging instruments:	3,581	182
Derivative assets
Derivative Asset [Abstract]
Total gross derivative instruments	82,668	35,007
Derivative liabilities
Derivative Liability [Abstract]
Total gross derivative instruments	27,349	15,516
Designated as hedging instrument \| Derivative assets
Derivative Asset [Abstract]
Derivatives designated as hedging instruments	0	0
Designated as hedging instrument \| Derivative assets \| Brokered time deposits
Derivative Asset [Abstract]
Derivatives designated as hedging instruments	0	0
Designated as hedging instrument \| Derivative liabilities
Derivative Liability [Abstract]
Derivatives designated as hedging instruments	144	880
Designated as hedging instrument \| Derivative liabilities \| Brokered time deposits
Derivative Liability [Abstract]
Derivatives designated as hedging instruments	144	880
Not designated as hedging instrument \| Derivative assets
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	82,668	35,007
Not designated as hedging instrument \| Derivative assets \| Customer derivative positions
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	74,793	27,277
Not designated as hedging instrument \| Derivative assets \| Dealer offsets to customer derivative positions
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	33	394
Not designated as hedging instrument \| Derivative assets \| Risk participations
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	0	0
Not designated as hedging instrument \| Derivative assets \| Mortgage banking - loan commitment
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	7,361	1,970
Not designated as hedging instrument \| Derivative assets \| Mortgage banking - forward sales commitment
Derivative Asset [Abstract]
Derivatives not designated as hedging instruments	481	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	27,205	14,636
Not designated as hedging instrument \| Derivative liabilities \| Customer derivative positions
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	33	446
Not designated as hedging instrument \| Derivative liabilities \| Dealer offsets to customer derivative positions
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	20,318	6,425
Not designated as hedging instrument \| Derivative liabilities \| Risk participations
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	28	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	4,281	86
Not designated as hedging instrument \| Derivative liabilities \| Bifurcated embedded derivatives
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	538	0
Not designated as hedging instrument \| Derivative liabilities \| Dealer offsets to bifurcated embedded derivatives
Derivative Liability [Abstract]
Derivatives not designated as hedging instruments	$ 2,007	$ 7,667

Fair value of securities received as collateral against derivative assets.

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