Derivative Instruments and Hedging Activities - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) swap	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) swap	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Derivative [Line Items]
Number of credit swaps | swap	22		22
Aggregate fair value of net liability position	$ 176,700,000		$ 176,700,000
Interest rate swaps
Derivative [Line Items]
Accumulated net after-tax losses related to effective cash flow hedges	5,900,000		5,900,000		$ 3,700,000
Estimated amount of interest rate derivatives to be reclassified to interest expense			4,500,000
Fair value hedge | Noninterest Income | Interest rate swaps
Derivative [Line Items]
Fee income related to derivative interest rate swaps executed with commercial loan customers	14,700,000	$ 5,400,000	28,900,000	$ 9,500,000
Derivatives designated as hedging instruments
Derivative [Line Items]
Notional amount	1,037,147,000		1,037,147,000		187,281,000
Derivatives designated as hedging instruments | Cash flow hedge
Derivative [Line Items]
Notional amount	900,000,000		900,000,000
Derivatives designated as hedging instruments | Fair value hedge | Interest rate swaps
Derivative [Line Items]
Notional amount	7,147,000		7,147,000		7,281,000
Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	7,852,326,000		7,852,326,000		4,255,866,000
Aggregate notional amount of derivative asset	166,400,000		166,400,000
Derivatives not designated as hedging instruments | Interest rate swaps
Derivative [Line Items]
Notional amount	$ 7,293,947,000		$ 7,293,947,000		$ 4,113,106,000
Derivatives not designated as hedging instruments | Fair value hedge | Interest rate swaps
Derivative [Line Items]
Number of instruments held | swap	2		2
Derivatives not designated as hedging instruments | Fair value hedge | Steepener swap, derivative one
Derivative [Line Items]
Notional amount	$ 10,400,000		$ 10,400,000
Derivatives not designated as hedging instruments | Fair value hedge | Steepener swap, derivative two
Derivative [Line Items]
Notional amount	$ 10,400,000.0		$ 10,400,000.0
Minimum | Derivatives designated as hedging instruments | Cash flow hedge
Derivative [Line Items]
Fixed interest rate	0.46%		0.46%
Maximum | Derivatives designated as hedging instruments | Cash flow hedge
Derivative [Line Items]
Fixed interest rate	0.67%		0.67%