Investment Securities - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Jun. 30, 2022	Sep. 30, 2021	Dec. 31, 2024
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 loss	$ 103,800,000
Available-for-sale, transfer to held-to-maturity, gain (loss)	0
Held to maturity mortgage backed securities	3,618,770,000				$ 3,639,850,000
Available for sale mortgage backed securities	2,828,940,000				2,852,774,000
Held-to-maturity, interest receivable	17,100,000
Available-for-sale, interest receivable	21,500,000
Available-for-sale securities	2,491,849,000				2,529,426,000
Securities valued at less than historical cost, amount	$ 2,412,227,000				2,467,223,000
Securities valued at less than historical cost (as percent)	96.80%
Provision for credit losses, AFS securities	$ 0	$ 0
Securities pledged as collateral	$ 2,220,000,000				2,360,000,000
Realized gains		0
Realized losses		$ 0
Income tax benefit related to security gains (losses) (as percent)	26.135%	26.135%
Commercial Mortgage Backed Securities
Debt Securities, Available-for-sale [Line Items]
Held to maturity mortgage backed securities	$ 134,200,000				136,000,000.0
Available for sale mortgage backed securities	515,900,000				517,200,000
Residential Mortgage Backed Securities
Debt Securities, Available-for-sale [Line Items]
Held to maturity mortgage backed securities	914,000,000.0				934,100,000
Available for sale mortgage backed securities	$ 865,000,000.0				$ 875,500,000