Derivatives and Hedging Activities - Gains and losses recognized in income on derivatives not designated as hedging instruments (Details) - Not designated as hedging instrument - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (231)	$ 599	$ 2,234	$ 1,335
Customer derivatives, dealer offsets and risk participations | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	2,258	648	4,846	2,371
Bifurcated embedded derivatives and dealer offsets | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	65	0	(158)	144
De-designated hedges | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	0	0	0	(193)
Mortgage banking derivatives | Mortgage loan revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (2,554)	$ (49)	$ (2,454)	$ (987)