Derivative Financial Instruments (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Derivative Financial Instruments
Notional Amount	$ 26,378,169,000		$ 26,378,169,000		$ 24,452,059,000
Derivatives assets	195,722,000		195,722,000		172,939,000
Derivative liabilities	606,194,000		606,194,000		804,486,000
Net gain (loss)			235,000
Fair value of the interest rate swap derivatives, other assets	193,900,000		193,900,000		169,000,000.0
Reduction in derivative asset fair value			412,500,000		635,300,000
Fair value of the interest rate swap derivatives, other liabilities	605,900,000		605,900,000		803,500,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Fair value of forward commitments	(606,194,000)		(606,194,000)		(804,486,000)
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	109,071,000		109,071,000		65,051,000
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	96,462,000		96,462,000		54,993,000
Cash flow hedge | Borrower
Derivative Financial Instruments
Collateral provided	263,400,000		263,400,000
Cash flow hedge | Counterparty
Derivative Financial Instruments
Collateral provided	98,100,000		98,100,000
Cash flow hedge | Interest-bearing deposits | Counterparty
Derivative Financial Instruments
Cash collateral	19,900,000		19,900,000
Economic hedges | Counterparty
Derivative Financial Instruments
Loss on derivative					5,000,000
Interest rate contracts
Derivative Financial Instruments
Notional Amount	24,300,000,000		24,300,000,000		22,600,000,000
Mortgage servicing rights hedging | Non-designated hedges
Derivative Financial Instruments
Notional Amount	146,000,000		146,000,000		142,000,000
Derivatives assets					2,605,000
Derivative liabilities	5,000		5,000
Estimated gain (loss) on fair value			5,000		2,600,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Fair value of forward commitments	(5,000)		(5,000)
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	1,685,000		1,685,000		1,154,000
Mortgage loan pipeline commitments hedging | Non-designated hedges
Derivative Financial Instruments
Notional Amount	126,000,000		126,000,000		77,500,000
Derivatives assets	1,685,000		1,685,000		1,154,000
Derivative liabilities	271,000		271,000		947,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Fair value of forward commitments	(271,000)		(271,000)		(947,000)
Forward commitments
Derivative Financial Instruments
Derivative liabilities	(271,000)		(271,000)		(947,000)
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	126,000,000		126,000,000		77,500,000
Fair value of forward commitments	271,000		271,000		947,000
Foreign exchange swaps
Derivative Financial Instruments
Gain or loss recorded	0	$ 0	0	$ 0
Interest rate swap
Derivative Financial Instruments
Net gain (loss)	(621,000)	$ 587,000	(235,000)	$ 599,000
Interest rate swap | Expected closures | Counterparty
Derivative Financial Instruments
Gain on derivative	27,000,000		28,000,000
Interest rate swap | Fair Value Hedging | Counterparty
Derivative Financial Instruments
Notional Amount	4,200,000		4,200,000		9,188,000
Amortized cost basis of loans hedged	4,000,000.0		4,000,000.0		9,700,000
Derivatives assets	81,000		81,000		220,000
Interest rate swap | Non-designated hedges | Borrower
Derivative Financial Instruments
Notional Amount	12,184,085,000		12,184,085,000		11,327,419,000
Derivatives assets	133,461,000		133,461,000		60,145,000
Derivative liabilities	605,734,000		605,734,000		803,539,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Fair value of forward commitments	(605,734,000)		(605,734,000)		(803,539,000)
Interest rate swap | Non-designated hedges | Counterparty
Derivative Financial Instruments
Notional Amount	12,093,484,000		12,093,484,000		11,235,952,000
Derivatives assets	60,467,000		60,467,000		108,820,000
Derivative liabilities	184,000		184,000
Reduction in derivative asset fair value			412,500,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Fair value of forward commitments	(184,000)		(184,000)
Interest rate swap | Economic hedges | Counterparty
Derivative Financial Instruments
Notional Amount	1,824,400,000		1,824,400,000		1,660,000,000
Derivative liabilities	(28,000)		(28,000)		5,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Fair value of forward commitments	$ 28,000		$ 28,000		$ (5,000)