Investment Securities - Narrative (Details)	3 Months Ended		12 Months Ended
	Jun. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($) bond	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, transfer to held-to-maturity	$ 1,990,000,000	$ 500,800,000
Debt securities, held-to-maturity transfer, unrealized gain			$ 108,100,000
Available-for-sale, transfer to held-to-maturity, gain (loss)			0
Held to maturity mortgage backed securities			3,639,850,000	$ 3,729,502,000
Available for sale mortgage backed securities			2,852,774,000	3,509,709,000
Held-to-maturity, interest receivable			20,300,000
Available-for-sale, interest receivable			24,100,000
Available-for-sale securities			2,529,426,000	3,152,153,000
Securities valued at less than historical cost, amount			$ 2,467,223,000	3,116,357,000
Securities valued at less than historical cost (as percent)			97.50%
Provision for credit losses, AFS			$ 0
Provision for credit loss expense				12,800,000
Net decrease in allowance on previously impaired securities				(3,722,000)
Securities charged-off				(7,000,000)
Securities pledged as collateral			2,360,000,000	3,320,000,000
Realized losses			$ 28,400,000	20,600,000	$ 324,000
Realized gains				$ 0	$ 46,000
Income tax benefit related to security gains (losses) (as percent)			26.135%	26.135%	26.135%
Commercial Mortgage Backed Securities
Debt Securities, Available-for-sale [Line Items]
Held to maturity mortgage backed securities			$ 136,000,000	$ 141,600,000
Available for sale mortgage backed securities			517,200,000	710,100,000
Residential Mortgage Backed Securities
Debt Securities, Available-for-sale [Line Items]
Held to maturity mortgage backed securities			934,100,000	1,020,000,000.00
Available for sale mortgage backed securities			875,500,000	1,230,000,000
Other securities
Debt Securities, Available-for-sale [Line Items]
Held to maturity mortgage backed securities			256,576,000	256,007,000
Available for sale mortgage backed securities			235,028,000	259,165,000
Available-for-sale securities			222,942,000	234,297,000
Securities valued at less than historical cost, amount			175,715,000	234,041,000
Provision for credit loss expense				12,800,000
Net decrease in allowance on previously impaired securities				(3,722,000)
Securities charged-off				$ (7,000,000)
Bonds
Debt Securities, Available-for-sale [Line Items]
Number of uncollectible bonds | bond				1
Investments sold, amount			$ 251,500,000	$ 247,900,000