Derivative Instruments - Hedge Derivatives (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Jun. 30, 2019
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	$ 16,500,000
Net loss (gain) on cash flow hedges reclassified from other comprehensive income into net income, net of tax	1,825,000	$ (256,000)
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 8,100,000
Notional Amount				$ 1,300,000,000
Not Designated as Hedging Instrument
Derivative [Line Items]
Description of Location of Gain (Loss) on Interest Rate Derivative on Income Statement	Other noninterest income	Other noninterest income
Notional Amount	$ 2,817,826,000		$ 2,592,778,000
Hedging derivative | Cash flow hedge
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	$ 63,769,000	$ (523,000)
Hedging derivative | Fair value hedge | Securities
Derivative [Line Items]
Weighted Average Remaining Maturity	6 years 9 months 14 days
Pay Rate (as percent)	3.08%
Derivative, Type of Interest Rate Paid on Swap	3 month LIBOR
Forecasted Notional Amount	$ 477,905,000		477,905,000
Fair Value Hedge Assets	(79,651,000)		(40,778,000)
Derivative Instruments and Hedges, Assets	$ 589,629,000		551,789,000
Description of Location of Gain (Loss) on Interest Rate Derivative on Income Statement	Interest income on securities
Description of Location of Interest Rate Fair Value Hedge Derivative on Balance Sheet	Other liabilities
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	$ 38,873,000	10,280,000
Gain (Loss) on Fair Value Hedges Recognized in Earnings	(38,873,000)	(10,280,000)
Fair Value Hedging Adjustment	$ 79,651,000		40,778,000
Hedging derivative | Fair value hedge | Loans
Derivative [Line Items]
Description of Location of Gain (Loss) on Interest Rate Derivative on Income Statement	Interest income on loans
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	$ 0	4,854,000
Gain (Loss) on Fair Value Hedges Recognized in Earnings	0	(4,854,000)
Amortization expense, reduction to interest income on loans	1,100,000
Pay fixed and receive variable swaps | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	1,408,913,000		1,296,389,000
Pay variable and receive fixed swaps | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	1,408,913,000		1,296,389,000
Asset derivatives | Hedging derivative | Cash flow hedge
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	$ 65,349,000	0
Description of Location of Interest Rate Cash Flow Hedge Derivative on Balance Sheet	Other assets
Weighted Average Remaining Maturity	4 years 8 months 8 days
Pay Rate (as percent)	0.00%
Receive Rate	2.25% minus 1 month LIBOR
Forecasted Notional Amount	$ 1,500,000,000		2,800,000,000
Cash Flow Hedges Derivative Instruments at Fair Value, Net	136,584,000		87,422,000
Liability derivatives | Hedging derivative | Cash flow hedge
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	$ (1,580,000)	$ (523,000)
Description of Location of Interest Rate Cash Flow Hedge Derivative on Balance Sheet	Other liabilities
Weighted Average Remaining Maturity	2 years 1 month 2 days
Pay Rate (as percent)	3.09%
Receive Rate	3 month LIBOR
Forecasted Notional Amount	$ 99,000,000		99,000,000
Cash Flow Hedges Derivative Instruments at Fair Value, Net	$ (5,453,000)		$ (3,312,000)