Derivative Financial Instruments (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Derivative Financial Instruments
Notional Amount	$ 29,748,406,000		$ 28,513,557,000
Estimated Fair Value Gain	177,262,000		161,490,000
Estimated Fair Value Loss	$ 698,933,000		$ 879,855,000
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Fair value of the interest rate swap derivatives, other assets	$ 175,100,000		$ 160,300,000
Reduction in derivative asset fair value	524,500,000		719,400,000
Fair value of the interest rate swap derivatives, other liabilities	698,400,000,000		878,000,000,000
Estimated gain (loss) on fair value	129,000		(1,800,000)
Mortgage loan pipeline
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	112,826,000		59,291,000
Expected closures
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	97,758,000		53,177,000
Cash flow hedge | Borrower
Derivative Financial Instruments
Collateral provided	262,400,000
Cash flow hedge | Interest-bearing deposits | Counterparty
Derivative Financial Instruments
Cash collateral	43,900,000
Interest rate contracts
Derivative Financial Instruments
Notional Amount	25,900,000,000		25,200,000,000
Mortgage servicing rights hedging | Non-designated hedges
Derivative Financial Instruments
Notional Amount	157,000,000		129,000,000
Estimated Fair Value Gain	$ 129,000
Estimated Fair Value Loss			$ 1,809,000
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Mortgage loan pipeline commitments hedging
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	$ 1,978,000		$ 751,000
Mortgage loan pipeline commitments hedging | Non-designated hedges
Derivative Financial Instruments
Notional Amount	135,000,000		88,000,000
Estimated Fair Value Gain	1,978,000		$ 1,083,000
Estimated Fair Value Loss	$ 541,000
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Forward commitments
Derivative Financial Instruments
Estimated Fair Value Loss	$ 541,000		$ (333,000)
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	135,000,000		88,000,000
Customer swaps | Cash flow hedge
Derivative Financial Instruments
Collateral provided	81,100,000
Foreign exchange swaps
Derivative Financial Instruments
Gain or loss recorded	0	$ 0
Interest rate swap
Derivative Financial Instruments
Gain or loss recorded	(172,000)	113,000
Interest rate swap | Fair Value Hedging | Counterparty
Derivative Financial Instruments
Notional Amount	3,898,000		3,945,000
Estimated Fair Value Gain	79,000		107,000
Amortized cost basis of loans hedged	$ 3,800,000		$ 3,800,000
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent
Interest rate swap | Non-designated hedges | Borrower
Derivative Financial Instruments
Notional Amount	$ 12,986,187,000		$ 12,649,905,000
Estimated Fair Value Gain	90,936,000		36,232,000
Estimated Fair Value Loss	$ 698,392,000		$ 878,046,000
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Interest rate swap | Non-designated hedges | Counterparty
Derivative Financial Instruments
Notional Amount	$ 12,880,321,000		$ 12,559,707,000
Estimated Fair Value Gain	84,154,000		124,032,000
Total gross derivative instruments, before netting, Notional amount	1,899,249,000		1,858,693,000
Total gross derivative instruments, before netting, Estimated fair value gain	100,639,000		(133,304,000)
Total gross derivative instruments, before netting, Estimated fair value loss	3,094,000		708,000
Less: Netting adjustment, Notional amount	172,329,000		49,000,000
Less: Netting adjustment, Estimated fair value gain	(3,094,000)		(708,000)
Less: Netting adjustment, Estimated fair value loss	(3,094,000)		(708,000)
Total gross derivative instruments, after netting, Notional amount	1,899,249,000		1,858,693,000
Total gross derivative instruments, after netting, Estimated fair value gain	97,545,000		132,596,000
Master netting arrangement collateral obligation to return cash offset against derivative asset	43,900,000		53,900,000
Securities pledged	30,000,000		$ 30,400,000
Master netting arrangement collateral obligation cash paid offset against derivative asset	$ 1,900,000
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Reduction in derivative asset fair value	$ 524,500,000		$ 719,400,000
Interest rate swap | Economic hedges | Counterparty
Derivative Financial Instruments
Notional Amount	3,586,000,000		3,083,000,000
Estimated Fair Value Gain	$ (14,000)	$ 1,000	$ 36,000
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other
Estimated Fair Value Loss	$ 14,000
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other		Noninterest Income, Other