Derivatives and Hedging Activities - Effect of derivatives in fair value hedging relationships (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments [Line Items]
Interest expense - deposits	$ 66,856	$ 39,543	$ 17,062
Interest revenue - taxable investment securities	69,920	73,496	70,172
Other noninterest income	28,775	24,142	16,477
Fair value hedge \| Interest expense - deposits
Gains (losses) on fair value hedging relationships:
Amounts related to interest settlements on derivatives	(327)	(245)	160
Recognized on derivatives	733	(220)	(657)
Recognized on hedged items	(766)	(145)	371
Net income (expense) recognized on fair value hedges	$ (360)	(610)	(126)
Fair value hedge \| Interest revenue - taxable investment securities
Gains (losses) on fair value hedging relationships:
Amounts related to interest settlements on derivatives		17	(302)
Recognized on derivatives		0	72
Recognized on hedged items		0	(265)
Net income (expense) recognized on fair value hedges		17	$ (495)
Fair value hedge \| Other noninterest income
Gains (losses) on fair value hedging relationships:
Amounts related to interest settlements on derivatives		0
Recognized on derivatives		356
Recognized on hedged items		(447)
Net income (expense) recognized on fair value hedges		$ (91)

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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