Loans and Allowance for Credit Losses for Loans - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non covered loans net of unearned discount and deferred loan fees	$ 119,100,000		$ 119,100,000		$ 120,500,000
Accrued interest	202,100,000		202,100,000		175,900,000
Sales of loans	0	$ 0	0	$ 0
Specific reserves for loan losses		56,000,000		56,000,000
Loan charge-offs related to loans modified as TDRs		1,500,000		1,500,000
TDRs not reported as non-accrual loans		67,300,000		67,300,000
Non-performing TDRs		$ 154,400,000		$ 154,400,000
Other real estate owned	824,000		824,000		286,000
Allowance for purchase credit deteriorated (PCD) loans			24,600,000
Residential real estate properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate owned	0		0		0
In formal foreclosure proceedings
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential mortgage and consumer loans secured by residential real estate properties	$ 454,000		$ 454,000		$ 2,600,000