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Loans and Allowance for Credit Losses - Additional Information (Details)			12 Months Ended
	May 01, 2025 USD ($)	Apr. 01, 2024 USD ($)	Dec. 31, 2025 USD ($) segment portfolio	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Loan participations			$ 3,800,000,000
Loan participations sold			1,900,000,000
Loan participations retained			$ 1,900,000,000
Number of loan portfolios | portfolio			4
Number of loan segments | segment			7
Allowance for credit losses at acquisition		$ 26,700,000
Provision for credit losses			$ 197,721,000	$ 110,619,000	$ 58,887,000
Accrued interest receivable on loans			$ 228,600,000	171,600,000
Loan placed on nonaccrual when past due, number of days			90 days
Financing receivable, modified, subsequent default			$ 6,500,000	8,800,000
Unfunded commitments on TDRs			0	0
CapStar Financial Holdings, Inc.
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses at acquisition			26,725,000	26,700,000
Provision for credit losses				$ 15,300,000
Bremer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses at acquisition	$ 103,500,000		103,546,000
Provision for credit losses			$ 69,100,000
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Percentage of risk-based capital			255.00%
Regulatory guideline limit			300.00%
Maximum
Financing Receivable, Allowance for Credit Losses [Line Items]
Aggregate amount of loans to related parties			5.00%	5.00%

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Amount, before allowance for credit loss, of accrued interest on financing receivable.

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