Derivative Financial Instruments (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended	18 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Jun. 30, 2024
Derivative Financial Instruments
Notional Amount	$ 25,563,807,000		$ 25,563,807,000		$ 24,452,059,000	$ 25,563,807,000
Derivatives assets	185,036,000		185,036,000		172,939,000	185,036,000
Derivative liabilities	955,347,000		955,347,000		804,486,000	955,347,000
Net gain (loss)			386,000
Fair value of the interest rate swap derivatives, other assets	182,400,000		182,400,000		169,000,000.0	182,400,000
Reduction in derivative asset fair value			774,000,000,000.0		635,300,000
Fair value of the interest rate swap derivatives, other liabilities	955,300,000		955,300,000		803,500,000	955,300,000
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	(955,347,000)		(955,347,000)		(804,486,000)	(955,347,000)
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	122,560,000		122,560,000		65,051,000	122,560,000
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	107,901,000		107,901,000		54,993,000	107,901,000
Cash flow hedge | Borrower
Derivative Financial Instruments
Collateral provided	270,400,000		270,400,000			270,400,000
Cash flow hedge | Counterparty
Derivative Financial Instruments
Collateral provided	96,400,000		96,400,000			96,400,000
Cash flow hedge | Interest-bearing deposits | Counterparty
Derivative Financial Instruments
Cash collateral	59,900,000		59,900,000			59,900,000
Economic hedges | Counterparty
Derivative Financial Instruments
Loss on derivative					5,000,000
Interest rate contracts
Derivative Financial Instruments
Notional Amount	23,600,000,000		23,600,000,000		22,600,000,000	23,600,000,000
Mortgage servicing rights hedging | Non-designated hedges
Derivative Financial Instruments
Notional Amount	122,000,000		122,000,000		142,000,000	122,000,000
Derivatives assets	500,000		500,000		2,605,000	500,000
Estimated gain (loss) on fair value			500,000		2,600,000
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	1,621,000		1,621,000		1,154,000	1,621,000
Mortgage loan pipeline commitments hedging | Non-designated hedges
Derivative Financial Instruments
Notional Amount	153,500,000		153,500,000		77,500,000	153,500,000
Derivatives assets	1,734,000		1,734,000		1,154,000	1,734,000
Derivative liabilities					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					(947,000)
Forward commitments
Derivative Financial Instruments
Derivative liabilities	113,000		113,000		(947,000)	113,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	153,500,000		153,500,000		77,500,000	153,500,000
Fair value of forward commitments	(113,000)		(113,000)		947,000	(113,000)
Foreign exchange swaps
Derivative Financial Instruments
Gain or loss recorded						0
Interest rate swap
Derivative Financial Instruments
Net gain (loss)	273,000	$ (84,000)	386,000	$ 12,000
Interest rate swap | Expected closures | Counterparty
Derivative Financial Instruments
Gain on derivative			1,000,000
Interest rate swap | Fair Value Hedging | Counterparty
Derivative Financial Instruments
Notional Amount	9,011,000		9,011,000		9,188,000	9,011,000
Amortized cost basis of loans hedged	9,500,000		9,500,000		9,700,000	9,500,000
Derivatives assets	393,000		393,000		220,000	393,000
Interest rate swap | Non-designated hedges | Borrower
Derivative Financial Instruments
Notional Amount	11,830,647,000		11,830,647,000		11,327,419,000	11,830,647,000
Derivatives assets	33,645,000		33,645,000		60,145,000	33,645,000
Derivative liabilities	955,347,000		955,347,000		803,539,000	955,347,000
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	(955,347,000)		(955,347,000)		(803,539,000)	(955,347,000)
Interest rate swap | Non-designated hedges | Counterparty
Derivative Financial Instruments
Notional Amount	11,732,649,000		11,732,649,000		11,235,952,000	11,732,649,000
Derivatives assets	148,765,000		148,765,000		108,820,000	148,765,000
Reduction in derivative asset fair value			774,000,000,000.0
Interest rate swap | Economic hedges | Counterparty
Derivative Financial Instruments
Notional Amount	1,716,000,000		1,716,000,000		1,660,000,000	1,716,000,000
Derivative liabilities	1,000		1,000		5,000	1,000
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	$ (1,000)		$ (1,000)		$ (5,000)	$ (1,000)