Derivative Instruments - Hedge Derivatives (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)		$ 16,500,000
Notional Amount		1,300,000,000
Loss on cash flow hedges reclassified from other comprehensive income into net income, net of tax	$ 504,000	1,825,000
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	4,700,000
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	3,236,566,000		$ 3,131,832,000
Hedging derivative | Cash flow hedge
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	(15,274,000)	63,769,000
Hedging derivative | Fair value hedge
Derivative [Line Items]
Forecasted Notional Amount	708,931,000		708,931,000
Fair Value Hedge Assets	(32,548,000)		(67,314,000)
Hedging derivative | Fair value hedge | Securities
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	34,766,000	(38,873,000)
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge	(34,766,000)	38,873,000
Derivative Instruments and Hedges, Assets	804,207,000		841,543,000
Fair Value Hedging Adjustment	32,548,000		67,314,000
Hedging derivative | Fair value hedge | Securities | LIBOR
Derivative [Line Items]
Forecasted Notional Amount	477,500,000
Hedging derivative | Fair value hedge | Securities | Federal Funds Rate
Derivative [Line Items]
Forecasted Notional Amount	231,400,000
Hedging derivative | Fair value hedge | Loans
Derivative [Line Items]
Amortization expense, reduction to interest income on loans	924,000	1,100,000
Pay fixed and receive variable swaps | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	1,618,283,000		1,565,916,000
Pay variable and receive fixed swaps | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	$ 1,618,283,000		1,565,916,000
Asset derivatives | Hedging derivative | Cash flow hedge
Derivative [Line Items]
Description of Location of Interest Rate Cash Flow Hedge Derivative on Balance Sheet	Other assets
Weighted Average Remaining Maturity	3 years 8 months 8 days
Pay Rate (as percent)	0.00%
Receive Rate	2.25% minus one-month LIBOR
Forecasted Notional Amount	$ 1,500,000,000		1,500,000,000
Cash Flow Hedges Derivative Instruments at Fair Value, Net	100,564,000		124,585,000
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	$ (15,274,000)	65,349,000
Asset derivatives | Hedging derivative | Fair value hedge | Securities
Derivative [Line Items]
Weighted Average Remaining Maturity	8 years 4 months 2 days
Pay Rate (as percent)	0.58%
Forecasted Notional Amount	$ 231,421,000		231,421,000
Description of Location of Interest Rate Fair Value Hedge Derivative on Balance Sheet	Other assets
Derivative, Type of Interest Rate Paid on Swap	Federal Funds
Fair Value Hedge Assets	$ 17,181,000		4,696,000
Liability derivatives | Hedging derivative | Cash flow hedge
Derivative [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	$ 0	$ (1,580,000)
Liability derivatives | Hedging derivative | Fair value hedge | Securities
Derivative [Line Items]
Weighted Average Remaining Maturity	5 years 9 months 14 days
Pay Rate (as percent)	3.08%
Forecasted Notional Amount	$ 477,510,000		477,510,000
Description of Location of Interest Rate Fair Value Hedge Derivative on Balance Sheet	Other liabilities
Derivative, Type of Interest Rate Paid on Swap	3 month LIBOR
Fair Value Hedge Assets	$ (49,729,000)		$ (72,010,000)