Loans and Allowance for Credit Losses - Narrative (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024 USD ($) loan	Jun. 30, 2023 USD ($) loan	Jun. 30, 2024 USD ($) loan	Jun. 30, 2023 USD ($) loan	Dec. 31, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 17,192,437,000		$ 17,192,437,000		$ 16,845,670,000
Deferred origination fees, net			265,000		6,700,000
Financing receivable, accrued interest excluded from amortized costs	79,500,000		79,500,000		77,100,000
Nonaccrual loans with no allowance for credit loss	$ 1,100,000		$ 1,100,000		3,200,000
Number of loan modifications | loan	1		1
Loan modified and subsequently defaulted			$ 23,000
Number of loan modifications with payment default | loan		0		0
Financing receivable, collateral dependent, amount	$ 110,613,000		$ 110,613,000		144,604,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, term of loan			1 year
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, term of loan			3 years
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans in process of foreclosure, amount	4,800,000		$ 4,800,000		2,500,000
OREO Received in Full or Partial Satisfaction of Loans | Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Foreclosed assets and other real estate owned	124,000		124,000		506,000
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	13,483,170,000		13,483,170,000		13,338,186,000
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded commitments, allowance for credit loss	25,600,000		25,600,000		25,600,000
Reserve for unfunded commitments, expensed (released)	0	$ 5,000,000	0	$ 5,000,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,769,655,000		2,769,655,000		2,722,886,000
Number of loan modifications | loan		1		1
Financing receivable, excluding accrued interest, modified				$ 655,000
Class of loans (in percent)				0.03%
Paycheck Protection Program Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,300,000		3,300,000		4,800,000
Other commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	7,760,266,000		7,760,266,000		7,552,410,000
Financing receivable, collateral dependent, amount	77,295,000		77,295,000		76,229,000
Single family residential | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 2,666,201,000		$ 2,666,201,000		2,641,556,000
Number of loan modifications | loan	1		1
Financing receivable, excluding accrued interest, modified			$ 663,000
Class of loans (in percent)			0.03%
Financing receivable, collateral dependent, amount	$ 0		$ 0		$ 3,870,000